SCGB2A1 and keratoconus: A protein that was only found by mass spectrometry only in the keratoconus subjects was a precursor to mammaglobin B. Mammaglobin B is a gene expressed in tumors of the esophagus, stomach, colon, pancreas, common bile duct, cholangioma and gall bladder, and is increased in breast cancer [40,41].