Metformin’s anti-tumor effects on various cancer types have revealed the role of dedicator of cytokinesis protein 1 (DOCK1), a canonical guanine nucleotide exchange factor (GEF) for Ras-related C3 botulinum toxin substrate (RAC) family small guanosine triphosphatases (GTPases), in influencing metformin’s efficacy in HCC [71]. The gene discussed is DOCK1; the disease is cancer.