Critically, ITGB4 knockdown abolished the chemoresistance promoted by exogenous FN1, which was associated with increased FAK (Y397) phosphorylation.<h4>Conclusion</h4>Our results demonstrate that the FN1-ITGB4 axis drives chemoresistance in bladder cancer via FAK signaling. The gene discussed is ITGB4; the disease is urinary bladder carcinoma.