In prostate cancer (PC), UBC9 mediates SUMOylation of signal transducer and activator of transcription 4 (STAT4) on K350 which activates the immunosuppressive phenotype of tumor-associated macrophages (TAMs), while macrophage-specific UBC9 ablation can facilitate STAT4-induced interplay among TAM-CD8(+) T cells-cancer cells to curb tumor progression [67]. This evidence concerns the gene UBE2I and pachyonychia congenita.