PRL and psoriasis: It is now appreciated that PRL is an important regulator of human hair growth [1], [6], [21], [74], [75] and may be implicated in the pathobiology of common, chronic skin diseases [6], [27] including psoriasis [3], [4], [5], [28], [52], [76], [77] and lupus erythematosus [7], [78], [79].