KANK1 and breast cancer: Finally, the LEC polarity in active mammary glands (Supplementary Fig. 2a), the gland morphology in pregnancy, lactation, and involution (Supplementary Fig. 3a) as well as the offspring numbers were normal in KANK1-null females (Supplementary Fig. 3b), indicating that mammary glands were unaltered prior to breast cancer induction.