SUB1 and breast cancer: Although overexpression of miR29a in MCF7 cells significantly downregulated the expression of PC4 both at transcript and protein level, we note that the levels of PC4 expression in the highly invasive Breast cancer cell lines like ZR-75-1 and HCC-38 is not comparable to the former condition (the PC4 levels were further down in ZR-75-1 and HCC-38).