The function of the normal BCR gene product is as a GTPase-activating protein for RAC1 and CDC42. Promotes the exchange of RAC or CDC42-bound GDP by GTP, thereby activating them. The protein has serine/threonine kinase activity. (1) | The function of the normal BCR gene product is as a GTPase-activating protein for RAC1 and CDC42. Promotes the exchange of RAC or CDC42-bound GDP by GTP, thereby activating them. The protein has serine/threonine kinase activity. (1) |