METTL14 is a tumor suppressor in UVB-induced skin cancer. (A and B) Percentage of tumor-free mice in WT and skin-specific METTL14 heterozygous conditional knockout (cHet, K14Cre;Mettl14fl/+) male (A) and female (B) mice following chronic UVB irradiation. n = 9 (WT male), n = 15 (cHet male), n = 15 (WT female), and n = 12 (cHet female). (C and E) Immunofluorescence staining of METTL14 (C) or DDB2 (E) in sham- and chronically UVB-irradiated mouse skin and skin tumors. (Scale bar, 20 μm.) (D and F) Quantification of METTL14 (D) or DDB2 (F) in C and E (mean ± SD, n = 4). (G) Positive correlation of DDB2 levels with METTL14 levels by Spearman test from C and E. (H) Immunofluorescence staining of METTL14 (red) in normal human skin (n = 7) and skin SCC tumors (n = 57). (Scale bar, 50 μm.) Cytokeratin (blue) is used as a keratinocyte marker. (I and J) Percentage of tumors (in stacked column format) for each score of METTL14 (I) or DDB2 (J). (K) Positive correlation of DDB2 levels with METTL14 levels by Spearman test from H. ***P < 0.001; Mann–Whitney U test (I and J), Student’s t test (D and F), and Log-rank test (A and B).