PPIB and melanoma: In a retrospective study examining the histological and immunohistochemical features of 65 cases of NUM in situ, Melan-A (also known as MART-1), human melanoma B (HMB) 45, and mouse monoclonal melanoma antibody (PNL2) showed superior diagnostic sensitivity compared to S-100 protein (>95% vs. 83.1%) [44].