The BR region interacts through an atypical basic-rich motif with the SH3D domain of the endocytic scaffolding protein intersectin leading to inhibition of CdGAP activity [19, 20] while the PRD is responsible for the ability of CdGAP to facilitate TGFβ-mediated cell motility and invasion of breast cancer cells [15] and to repress E-cadherin expression [17]. Here, ARHGAP31 is linked to breast cancer.