GTPase-activating protein for RHOA and CDC42. Facilitates mitochondrial quality control by promoting Parkin-mediated recruitment of autophagosomes to damaged mitochondria (PubMed:38081847). Negatively regulates the growth of human parainfluenza virus type 2 by inhibiting hPIV-2-mediated RHOA activation via interaction with two of its viral proteins P and V (PubMed:27512058). ; [Isoform 2]: Associates with MICAL1 on the endosomal membrane to promote Rab8-Rab10-dependent tubule extension. After dissociation of MICAL1, recruits WDR44 which connects the endoplasmic reticulum (ER) with the endosomal tubule, thereby participating in the export of a subset of neosynthesized proteins.