ADGRD1 and pemphigus: Progesterone, a multifunctional hormone traditionally used for contraception, managing abnormal uterine bleeding, and preventing endometrial hyperplasia, was found to interact with the GPCR target ADGRD1 (Q6QNK2) through repositioning via a nuclear receptor, as shown in Figure 5A. This interaction is linked to various indications, including pemphigus, atopic dermatitis, and breast cancer.