ERBB2 and breast cancer: Knockdown of SH3GL1 in HER2-positive HCC1954 and SK-BR-3 breast cancer cells reduced HER2 internalisation and markedly suppressed T-DM1-mediated cytotoxicity.41 Endophilin A2 might, therefore, provide an effective marker of intrinsic sensitivity to T-DM1 given its potential role in T-DM1 internalisation and the association of SH3GL1 expression with poor relapse-free survival and OS in patients with node-positive, HER2-positive breast cancer;41 however, further investigation in additional experimental models is required.