ERBB2 and cancer: Hence, we hypothesized that mutp53 allele may sensitize ErbB2 expressing cells to lapatinib by two complementary mechanisms: 1) mutp53 mediated amplification of ErbB2 signaling [17] that creates superior dependency of cancer cells on ErbB2 signaling, and 2) lapatinib induced mutp53 degradation (Figures 1, 2).