ESR2 and urinary bladder cancer: Mast cells have been reported to play a pro-tumorigenic role in human bladder cancer through the stimulation of estrogen receptor β (ERβ).522 Accordingly, a selective EBβ antagonist inhibited mast cell-promoted tumor growth in a murine model of bladder cancer.522 Besides, mast cells were also shown to promote the proliferation of colon cancer in vivo, while injection of the Fcε-PE40 chimeric toxin, known to induce the apoptosis of mast cells, led to retrogradation of colon tumor progression in vivo.523