(A) Protein level of RTL1 in Hacat, A375 and A875 cells. The protein level was analyzed by Densitometry, compared with the Hacat cells * p<0.05; (B) mRNA level of the RTL1 expression in Hacat, A375 and A875 cells, RTL1 expression was higher in two melanoma cells, ** p<0.01; (C-D) western blot and QPCR assays for the overexpression and knockdown efficiency of RTL1; the protein level was analyzed by Densitometry, compared with control group * p<0.05 and ** p<0.01; (E) CCK8 and cell count assay for cell proliferation of A375 cells with RTL1 overexpression. RTL1 accelerated cell proliferation; * p<0.05, ** p<0.01 and *** p<0.001; (F) Fluorescence Activating Cell Sorter (FACS) assay assessing the cell cycle phases of A375 cells with RTL1 overexpression * p<0.05. And QPCR assay detecting expression of cell cycle-related genes; the RTL1 affected the expression of E2F1, CDK6, CYCLIN D1 and c-MYC, * p<0.05; (G and I) CCK8 and cell count assay for cell proliferation of A375 cells with RTL1 knockdown, * p<0.05, ** p<0.01 and *** p<0.001; (H and J) FACS assay assessing the cell cycle phases of A375 cells with RTL1 knockdown, * p<0.05. And QPCR assay detecting expression of cell cycle-related genes; the RTL1 affected the expression of E2F1, CDK6, CYCLIN D1 and c-MYC, * p<0.05 and ** p<0.01; (K) Western blot analysis of cell cycle-related proteins in A375 cells with RTL1 overexpression or knockdown; (L) the protein level in (K) was analyzed by Densitometry, compared with the control group (FUGW and Tet-on shRNA without DOX), * p<0.05, ** p<0.01 and *** p<0.001.