ANXA5 and breast cancer: Apoptotic cell death analysis was performed using the FITC: Annexin-V Apoptosis Detection Kit I. Both lapatinib and ganetespib treatment resulted in a notable early apoptotic cell population compared to untreated control cells, and combination treatment caused an even more significant increase in early apoptosis, demonstrating that joint administration can induce cell death via apoptosis in both lapatinib-sensitive and -resistant breast cancer cell lines (Figures 3A,B).