STAT3 and breast cancer: Evidence also showed that FoxO1 expression could be transcriptionally decreased by activating STAT3 signalling.31 And in breast cancer cell lines, combination therapy of trastuzumab and MPA markedly decreased constitutive activation of STAT3 and resulted in higher expression of proapoptotic factors such as p27 and FoxO1.44 Hence, we showed that overexpression of EZH2 decreased levels of FoxO1 transcriptionally and translationally and down‐regulation of STAT3 led to increased expression of FoxO1 in both mRNA and protein levels.