- CD44v3 ICD was shown to interact with Vav2, a GDP/GTP exchanger for Rac1- HA increased the rate of Vav2-mediated GDP/GTP exchange reaction compared to untreated cells- HA treatment stimulated ERBB2 activity and caused a significant increase in the amount of CD44v3 complex-associated ERBB2, Grb2 and Vav2- The formed complex lead to Ras signaling activation and tumor growth promotion. Here, GRB2 is linked to neoplasm.