JMJD1C is a histone demethylase belonging to the KDM3 family with both catalytic and non-catalytic functions critical for multiple biological processes. As a histone H3K9 demethylase, JMJD1C regulates chr10 remodeling and gene expression 1. Beyond its canonical demethylase activity, JMJD1C demethylates non-histone substrates, particularly STAT3 at lysine 140, to restrain plasma cell differentiation and prevent rheumatoid arthritis development 2. JMJD1C is essential for tumor regulatory T cell fitness through H3K9me2 demethylation and STAT3 signaling, making it a selective therapeutic target for enhancing antitumor immunity without systemic autoimmunity 3. In acute myeloid leukemia, JMJD1C forms biomolecular condensates and interacts with transcription factor RUNX1 to facilitate leukemic survival programs 4. JMJD1C is genotype-specifically required for IDH2- and TET2-mutant hematopoietic stem cell fitness 5 and regulates megakaryopoiesis through actin network modulation 6. Additionally, JMJD1C participates in renal epithelial-mesenchymal transition in diabetic kidney disease through SP1/ZEB1 signaling 7. Genomic studies implicate JMJD1C as a target of endocrine disruptors influencing estrogen receptor-positive breast cancer risk 8.