GJB2 and breast cancer: Comparing mice treated with DMBA 3 months after pituitary isografts, the average tumour growth rate were non-significantly different between Cre- (49±30 mm3/day) and Cre+ (81±39 mm3/day) mice suggesting that Cx26 knockout prior to mammary tumour onset did not predispose the gland to primary tumors with increased growth rate (Figure 3B).