SLC44A4 encodes a thiamine pyrophosphate transporter (TPPT) that plays a critical role in colonic uptake of vitamin B1 from gut microbiota 1. The transporter demonstrates colon-specific expression along the gastrointestinal tract and is predominantly or solely responsible for carrier-mediated thiamine pyrophosphate (TPP) uptake in colonocytes 1. Mechanistically, SLC44A4 expression is regulated by transcription factors ELF3 and CREB-1, which drive basal promoter activity in colonic epithelial cells 2. The colon-specific expression pattern is controlled by epigenetic mechanisms, including histone modifications where histone H3 shows activating marks (trimethylation at lysine 4, acetylation at lysine 9) in colon but repressive marks (trimethylation at lysine 27) in other tissues 3. SLC44A4 expression can be downregulated by pathogenic factors, as demonstrated by EHEC infection reducing transporter expression through ERK1/2 and NF-κB signaling pathways 4. Beyond its physiological role, SLC44A4 knockout mice show increased susceptibility to colitis and inflammation, supporting genome-wide association studies identifying it as a potential colitis susceptibility gene 1. The transporter has also gained attention as a therapeutic target, with SLC44A4-targeted antibody-drug conjugates being developed for epithelial tumors, particularly pancreatic and prostate cancers 5.