RACK1 and melanoma: To understand whether RACK1 was related to the tumorigenesis of melanoma, We first examined the expression of RACK1 in melanoma cell lines (A375 and A875) and the normal skin cell line HaCaT, both mRNA and protein levels of RACK1 in A375 and A875 cells were higher than that in HaCaT (P<0.05) (Fig. 1A and B).