GPER1 and breast cancer: Thymidine uptake studies also indicate that the non-aromatizable androgen metabolite, dihydrotestosterone, DHT-induced [3H]-thymidine incorporation can be inhibited by ICI 182,780, a pure anti-estrogen that serves as an antagonist of the ER in ER-α-positive MCF-7 breast cancer cells [11, 12] in which other ERs such as ER-β, GPR30 and ER-α spliced variants such as ER-α36, and ER-α46 also exist [13–16].