CDC42 and endometriosis: While it is not yet clear how the variants in these genes might lead to an increased risk of developing endometriosis and/or uterine fibroids, a mechanistic connexion can be postulated more obviously in some cases than others: CDC42 (cell division cycle 42) encodes a small Rho GTPase of a family of proteins regulating the cell cycle (39), while WNT4 (Wingless-Type MMTV Integration Site Family, Member 4) encodes a ligand that interacts with the β-Catenin signalling pathway to control self-renewal in adult tissues by acting on somatic stem cells (40).