PRL and pituitary gland adenoma: This present study used 2DGE, 2DGE-based Western blotting, and MS to detect and identify hPRL variants in human pituitaries and differentially expressed profiles of hPRL variants among different subtypes of pituitary adenomas relative to controls, which will provide novel clues to further study the functions, and mechanisms of action, of hPRL in human pituitary and in PRL-related diseases, and the potential clinical value in pituitary adenomas.