Seems to be involved in regulation of transcriptional activity of MYC. In vitro, inhibits DNA-binding activity of Mad-MAX heterodimers. Can recruit Mad transcriptional repressors (MXD1, MXD3, MXD4 and MXI1) to the cytoplasm. May be involved in spermiogenesis (By similarity). . This is the function of RNF17 (ring finger protein 17, Ensembl gene identifier ENSG00000132972).