RAC1 and cancer: V-ATPase could promote invasion and migration of cancer cells by modulating pH of the lumen of intracellular organelles required for the activation of lysosomal proteases important for the regulation of key cell signaling pathways such as the epidermal growth factor receptor (EGFR) signaling cascade that, through the activation of the GTPase RAC1 (Ras-related C3 botulinum toxin substrate 1), controls cell motility18–20.