Cdc42-overexpressing mammary glands do not display defects in apical or basal-lateral polarity or development of the myoepithelial or luminal cell compartments. (A) Representative images of TEBs from control and Cdc42-overexpressing mice immunostained to detect the apical surface marker phosphorylated ERM (n = 5 animals per genotype with at least three TEBs analyzed per animal). Scale bars = 20 μm. (B) Representative TEBs immunostained using antibodies against E-cadherin and keratin 14 to visualize the body and myoepithelial cell compartments, respectively (n = 5 animals per genotype with at least three TEBs analyzed per animal). E-cadherin marks the surface of the body cells. Arrow indicates gap in myoepithelial layer at a bud forming off a large TEB. Scale bars = 50 μm. (C) Representative images of mature ducts immunostained to detect keratins 8 and 14 (n = 5 animals per genotype). Scale bars = 20 μm. Cdc42, cell division cycle 42; ERM, ezrin-radixin-moesin; TEB, terminal end bud.