ERBB2 and breast cancer: In agreement with our hypothesis that Mcl-1 regulates Her2 and downstream Hif-1α protein levels in BC cells under hypoxic conditions, treatment with CoCl2 increased Hif-1α protein levels in a dose-dependent (Fig. 2c) and time-dependent (Fig. 2d) manner, without changing Mcl-1 or Her2 levels.