ERBB2 and neoplasm: Since loss of either Nedd9 or p130Cas/BCAR1 impairs growth of ErbB2 tumours, the full activation of crucial ErbB2 downstream effectors, such as Src and FAK, may require the co-expression of Nedd9 and p130Cas/BCAR1, suggesting that these two Cas proteins cooperate during early ErbB2 tumourigenesis (Figure 3B).