If the tender offer is terminated and the transaction is to be effected by merger only, in which case, the approval of Checkmate stockholders must be obtained, Regeneron, Checkmate and their respective directors and executive officers may be deemed to be participants in any such solicitation of proxies from Checkmate's stockholders in connection with the proposed transaction. Information regarding Regeneron's directors and executive officers is available in its proxy statement that was filed with the SEC; information regarding Checkmate's directors and executive officers is available in its proxy statement that was filed with the SEC. Other information regarding potential participants in any such proxy solicitation will be contained in any proxy statement filed in connection with the transaction.