PTPRR and melanoma: The second region of SSC5 spanned 430 kb between 37.6 and 38.1 Mb, with the strongest association signal (p = 3.7 × 10–5) located between PTPRR (Protein Tyrosine Phosphatase, Receptor Type R), a negative regulator of the MAPK pathway [39], and TSPAN8 (Tetraspanin 8), a key regulator of melanoma invasion [40, 41].