KRT38 (keratin 38) is a type I intermediate filament protein that serves as a structural component of hair follicles and skin epidermis 1. KRT38 expression occurs in wool and hair follicles during the anagen (growth) phase, with transcription proceeding in a spatially organized pattern from the germinal matrix outward, and expression ceases during follicle dormancy (telogen) 1. The gene is expressed primarily in the cortical cells of hair fibers, contributing to fiber architecture and morphology 2. Regulation of KRT38 appears mediated by transcription factors including HOXC13, which upregulates KRT38 promoter activity during hair follicle differentiation 3. Notably, KRT38 is significantly downregulated in alopecia areata (AA) lesional scalp tissue, clustering with other type I keratins (KRT31-35) whose reduced expression correlates with disrupted hair follicle structure and function in this immune-mediated inflammatory condition 4. Additionally, KRT38 has been identified as a potential prognostic marker in metastatic muscle-invasive bladder cancer, where altered expression may contribute to disease progression 5, and was detected as a cancer stem cell-specific mutation in colorectal cancer metastasis 6. These findings suggest KRT38 plays critical roles in hair follicle maintenance and potentially in cancer biology beyond its primary structural function.