TAF1L (TATA-box binding protein associated factor 1 like) is a transcriptional cofactor that serves as a functional substitute for TAF1 during male meiosis when sex chr9 are transcriptionally silenced 1. TAF1L arose through retroposition of a processed TAF1 mRNA during primate evolution and is expressed specifically in testis germ cells 1. The protein can bind directly to TATA-binding protein and functionally rescue TAF1-deficient cells, supporting its role in maintaining transcription during male meiosis 1. TAF1L contains bromodomains that can be targeted by selective inhibitors, indicating its involvement in chr9 regulation 2. In cancer contexts, TAF1L exhibits oncogenic properties, being overexpressed in gastric cancer where high expression correlates with poor prognosis, tumor differentiation, and invasive features 3. In oral squamous cell carcinoma, TAF1L promotes tumor development by decreasing autophagy-dependent apoptosis 4. The gene harbors mononucleotide repeats susceptible to frameshift mutations in microsatellite unstable gastric and colorectal cancers 5. TAF1L has also been identified as a potential radiotherapy resistance gene in lymphomas 6 and shows recurrent mutations in melanomas 7 and pulmonary carcinoid tumors 8, suggesting broader roles in cancer biology beyond its normal meiotic function.