POLR2J encodes RNA polymerase II subunit J (hRPB11), a core component of RNA polymerase II that synthesizes mRNA precursors and functional non-coding RNAs 1. The POLR2J gene family consists of multiple genes (POLR2J1-4) located on human chromosome 7, producing at least 14 different mRNA isoforms through alternative splicing 2. These isoforms show functional diversity: the hRPB11bα isoform specifically interacts with transcription factor ATF4, enhancing its transcriptional activation by 2.5-fold through direct contact without requiring Mediator complex involvement 1. Another minor isoform, hRPB11cα, interacts with translation initiation factor eIF3 subunits (eIF3a, eIF3i, eIF3m), suggesting coordination between transcription and downstream gene expression processes 3. POLR2J has emerged as a disease-relevant gene, identified as a potential oncogene in basal-like breast cancer with driver mutations in its promoter region 4. The gene also shows associations with immune-mediated necrotizing myopathy, cryptorchidism, and sepsis through bioinformatics analyses 567. The POLR2J gene family serves as a molecular marker for higher primate evolution, with its structure correlating with anthropogenesis stages 8.