Pricing Term Sheet

Dated June 22, 2011

Issuer:

Ticker / Exchange for

Common Stock:

Securities Offered:

Aggregate Principal

Amount Offered:

Maturity Date:

Interest Rate:

Interest Payment Dates:

NASDAQ Last Reported

Sale Price on June 22, 2011:

Conversion Premium:

Initial Conversion Price:

Initial Conversion Rate:

Use of Proceeds:

The Issuer estimates that the proceeds from the Offering will be approximately $340,650,000 (or $391,837,500 if the underwriters exercise their over-allotment option to purchase additional Notes in full), after deducting underwriters’ discounts and estimated offering expenses.

The Issuer entered into convertible note hedge transactions with one or more of the underwriters or their affiliates (the “Counterparties”). The Issuer also entered into warrant transactions with the Counterparties. The Issuer intends to use approximately $28,000,000 of the net proceeds from the Offering to pay the cost of the convertible note hedge transactions (after such cost is partially offset by the proceeds to the Issuer from the sale of the warrant transactions). If the underwriters exercise their overallotment option to purchase additional Notes, the Issuer may sell additional warrants and use a portion of the net proceeds from the sale of the additional Notes and from the sale of additional warrants to enter into additional convertible note hedge transactions.

The Issuer intends to use the remainder of the net proceeds from the Offering for general corporate purposes and to purchase up to $230,000,000 in aggregate principal amount of its outstanding 2.25% Existing Senior Convertible Notes due 2013 (the “Existing Notes”). See “Use of Proceeds” in the Preliminary Prospectus.

Commissions and

Discounts:

Public offering price ⁽¹⁾

Underwriting discounts and commissions

Proceeds, before expenses, to the Issuer

Plus accrued interest, if any, from June 28, 2011

Joint Book-Running

Managers:

BofA Merrill Lynch

Goldman, Sachs & Co.

Adjustment to Conversion

Rate Upon a Make-Whole Fundamental Change:

Stock Price

$32.41

$35.00

$40.00

$42.13

$45.00

$50.00

$60.00

$80.00

$100.00

$125.00

$150.00

$200.00

if the stock price is between two stock price amounts in the table or the make-whole reference date is between two dates in the table, the number of additional shares will be determined by a straight-line interpolation between the number of additional shares set forth for the higher and lower stock price amounts and the two dates, as applicable, based on a 365-day year;

if the stock price is greater than $200.00 per share, subject to adjustment in the same manner as the stock prices set forth in the row headers of the table above, no increase will be made to the conversion rate; and

if the stock price is less than $32.41 per share, subject to adjustment in the same manner as the stock prices set forth in the row headers of the table above, no increase will be made to the conversion rate.

Existing Senior Convertible Notes due 2013

Convertible Senior Notes due 2017(1)

Other long-term liabilities

Noncontrolling interests

Stockholders’ equity: (2)

Preferred stock, $0.001 par value; 5,000 shares authorized, none outstanding

Common stock, $0.001 par value; 70,000 shares authorized, 39,652 issued and outstanding

Additional paid-in capital

Accumulated other comprehensive income

Accumulated deficit

Total stockholders’ equity

Total capitalization

7,109,395 shares of common stock issuable upon the exercise of options to purchase the Issuer’s common stock outstanding at March 31, 2011, at a weighted average exercise price of $30.00 per share;

1,005,953 shares of common stock issuable upon the vesting of restricted stock unit awards outstanding at March 31, 2011;

2,056,426 shares of common stock reserved for future issuance under the Issuer’s 2004 Employee Stock Purchase Plan at March 31, 2011;

5,140,845 shares of common stock issuable upon the exercise of warrants outstanding at March 31, 2011 at an exercise price of $49.13 per share;

5,140,845 shares of common stock issuable upon the conversion of Existing Senior Convertible Notes outstanding at March 31, 2011;

10,799,110 shares that may become issuable upon the conversion of the Notes (assuming no exercise of the over-allotment option), assuming the requisite stockholder approvals; and

16,614,080 shares that may become issuable upon conversion of the Series A participating preferred stock issuable upon exercise of the warrant transactions entered into by the Issuer concurrently with the pricing of the Notes (excluding any warrant transactions that we may enter into if the underwriters exercise the over-allotment option), assuming the requisite stockholder approvals.

Change From Preliminary

Prospectus:

The following sentence shall replace the third sentence in the final paragraph on page 94 of the Preliminary Prospectus in the section entitled “Underwriting”:

“Notwithstanding the above, this lock-up provision will not apply to us with respect to, among other things, (1) the grant of any warrant to any of the underwriters or their affiliates and transfers or sales of shares of common stock, each pursuant to the convertible note hedge and warrant transactions executed by us concurrently with the pricing of the notes and (2) issuances of our common stock, options, warrants or other convertible or exchangeable securities relating to our common stock to any third party as consideration in connection with any merger, acquisition, business combination or other strategic or commercial relationship, in an amount not to exceed 6% of our fully-diluted shares of common