ESR1 and urinary bladder cancer: In particular, recent investigation, based on striking sex-specific differences in its incidence [1,2], has suggested critical roles of sex hormone receptors, including androgen receptors (AR) (i.e., stimulation) and estrogen receptors (ERs) (i.e., both stimulation and inhibition, potentially dependent on the functional activity of the ERα versus ERβ), in bladder cancer [8,9].