TGFB1 and urinary bladder cancer: Similarly, in bladder cancer, the high recurrence rates and heterogeneity of muscle-invasive vs. non-muscle-invasive disease have spurred investigations into stromal–epithelial interactions mediated by transforming growth factor beta 1 (TGF-β1) and other cytokines, aiming to predict progression more accurately than cystoscopy or cytology alone [8].