The altered expression of a number of molecular markers, including the progesterone, estrogen, and prolactin receptors, the Na/K/2Cl cotransporter proteins (NKCC1) and aquaporin 5 (AQP5), and several markers of skin differentiation (Sprr2A and keratin 6) has been reported in breast cancer [69]. The gene discussed is AQP5; the disease is breast carcinoma.