YES1 was amplified in BT-474-R and further amplified in BT-474-R/TDR (Figure 3A)....In both assays, the combination of T-DM1 with dasatinib was found to be effective in BT-474-R and BT-474-R/TDR....In BT-474-R/TDR, there was no apoptosis with dasatinib alone, but apoptosis was induced by the combination therapy.