Investors and security holders of Pharmacyclics are urged to read the tender offer statement on Schedule TO, filed on March 23, 2015 (as amended, the "Schedule TO"), the Registration Statement on Form S-4, as filed on March 23, 2015 (as amended, the "Registration Statement"), and the solicitation/recommendation statement filed by Pharmacyclics on Schedule 14D-9, filed on March 23, 2015 (as amended, the "Schedule 14D-9"). The tender offer materials (including an offer to purchase, letter of transmittal and related tender offer documents), the Registration Statement and the Schedule 14D-9 contain important information which should be read carefully before any decisions are made with respect to the Offer.