NRAS and melanoma: Among the latter, in recent years, upregulation of CCND1/cyclin D1 dependent on activation of the MAPK pathway (Ras/Raf/MEK/Erk) has been reported, with the MAPK pathway constitutive activation being observed in 90% of melanomas [53], in which the BRaf and NRas mutations [54,55] are especially important.