tokens: We have compared the ability of GST - Bem3 to serve as a GAP for Cdc42Hs relative to other members of the rho - GAP subfamily and found the following order of potency : human platelet Cdc42Hs GAP > p190 > Bem3 > break point cluster region protein , whereas p85 , like Bem2 , shows no GAP activity or any ability to bind to the GTP - bound form of Cdc42Hs .