FOXA3 (forkhead box A3) is a transcription factor that functions as a 'pioneer' factor, opening compacted chr19 for other proteins by interacting with nucleosomal core histones 1. FOXA3 plays critical roles in metabolic homeostasis and liver development, with expression patterns defining pancreatic progenitor tumors that preferentially express early pancreatic developmental genes including FOXA3 2. The protein can be successfully used for direct reprogramming of human fibroblasts to functional hepatocytes when co-expressed with HNF1A and HNF4A 3. In disease contexts, FOXA3 contributes significantly to non-alcoholic fatty liver disease (NAFLD) progression through an XBP1s-FOXA3-PER1/SREBP1c transcriptional axis that enhances lipid synthesis under endoplasmic reticulum stress 4. FOXA3 also regulates cholesterol metabolism in metastatic lung adenocarcinoma by transcriptionally activating HMGCS1, promoting endogenous cholesterol biosynthesis essential for cancer cell migration 5. Additionally, FOXA3 serves as a key transcription factor for the iCMS3 colorectal cancer subtype 6. Genetic variants in FOXA3, particularly rs28666870, are associated with metabolic traits including body mass index and lean body mass in humans 7.