EXHIBIT 99.1 SIGNATURES FOR FORM 4 SANOFI-AVENTIS By: /s/ John Felitti --------------------------------------------- Name: John Felitti Title: Associate Vice President, Corporate Law, Financial & Securities Law Date: April 8, 2011 GC Merger Corp. By: /s/ Gregory Irace --------------------------------------------- Name: Gregory Irace Title: President Date: April 8, 2011