The function of ENSG00000170421 (KRT8, keratin 8) is as follows. Structural component of intermediate filaments in simple epithelial cells. Together with its obligate type I partner KRT18, contributes to the formation of the keratin intermediate filament network that provides mechanical stability and resilience to epithelial cells (PubMed:26823019). Also involved in maintaining epithelial integrity and protecting cells from non-mechanical stress, such as apoptosis (By similarity). Also required for ARHGEF40-mediated actin stress fiber formation and tensional force-induced stress fiber formation and reinforcement (PubMed:26823019). In striated muscle, together with KRT19, may contribute to linking the contractile apparatus to dystrophin at the costameres (PubMed:16000376). {ECO:0000250|UniProtKB:P11679, ECO:0000269|PubMed:16000376, ECO:0000269|PubMed:26823019}.