APOL1-mediated monovalent cation transport contributes to APOL1-mediated podocytopathy in kidney disease. Two coding variants of apolipoprotein L1 (APOL1), G1 and G2, are associated with increased risk of kidney disease in African Americans. While various cytotoxic phenotypes have been reported in experimental models, the proximal mechanism by which G1 and G2 cause kidney disease is poorly understood. This study used three experimental models and a small molecule blocker of APOL1, VX-147, to identify the upstream mechanism of G1-induced cytotoxicity. In HEK293 cells, G1-mediated Na⁺ import/K⁺ efflux triggered activation of GPCR/IP3-mediated calcium release from the ER, impaired mitochondrial ATP production, and impaired translation, which were reversed by VX-147. In human urine-derived podocyte-like epithelial cells (HUPECs), G1 caused cytotoxicity that was reversed by VX-147. In podocytes isolated from APOL1 G1 transgenic mice, IFN-γ-mediated induction of G1 caused K⁺ efflux, activation of GPCR/IP3 signaling, and inhibition of translation, podocyte injury, and proteinuria, all reversed by VX-147. These results establish APOL1-mediated Na⁺/K⁺ transport as the proximal driver of APOL1-mediated kidney disease. APOL1 variants G1 and G2 are associated with increased risk of chronic kidney disease in African Americans. The mechanism by which G1 and G2 cause kidney disease is poorly understood. Cell-based and transgenic animal models show that RRVs cause cellular injury and cell death, whereas the reference APOL1 G0 is relatively nontoxic. The mechanism by which RRVs induce cytotoxicity in experimental models is believed to mirror the pathomechanism of APOL1-mediated kidney disease. Therefore, elucidation of the mechanism of RRV-induced cytotoxicity is a major priority. Experimental models have failed to produce a unified mechanism that explains the multiple cytotoxic phenotypes caused by RRVs. Prior studies show that in a planar lipid bilayer, APOL1 protein forms a cation-selective pore that is permeable to Na⁺ and K⁺. In a HEK cellular model with inducible expression of APOL1 G0, G1, or G2, APOL1 also forms cation pores in the plasma membrane of mammalian cells, but only G1 and G2 cause aberrant influx of Na⁺ and efflux of K⁺, leading to cellular swelling, activation of JNK and p38 MAPK, and cellular death. Based on these results, we proposed that the cation pore function of RRVs is the proximal driver of cytotoxicity. While other investigators have confirmed our observation that RRVs cause K⁺ efflux and NaAPOL1-mediated monovalent cation transport contributes to APOL1-mediated podocytopathy in kidney disease. Two coding variants of apolipoprotein L1 (APOL1), G1 and G2, are associated with increased risk of kidney disease in African Americans. While various cytotoxic phenotypes have been reported in experimental models, the proximal mechanism by which G1 and G2 cause kidney disease is poorly understood. This study used three experimental models and a small molecule blocker of APOL1, VX-147, to identify the upstream mechanism of G1-induced cytotoxicity. In HEK293 cells, G1-mediated Na⁺ import/K⁺ efflux triggered activation of GPCR/IP3-mediated calcium release from the ER, impaired mitochondrial ATP production, and impaired translation, which were reversed by VX-147. In human urine-derived podocyte-like epithelial cells (HUPECs), G1 caused cytotoxicity that was reversed by VX-147. In podocytes isolated from APOL1 G1 transgenic mice, IFN-γ-mediated induction of G1 caused K⁺ efflux, activation of GPCR/IP3 signaling, and inhibition of translation, podocyte injury, and proteinuria, all reversed by VX-147. These results establish APOL1-mediated Na⁺/K⁺ transport as the proximal driver of APOL1-mediated kidney disease. APOL1 variants G1 and G2 are associated with increased risk of chronic kidney disease in African Americans. The mechanism by which G1 and G2 cause kidney disease is poorly understood. Cell-based and transgenic animal models show that RRVs cause cellular injury and cell death, whereas the reference APOL1 G0 is relatively nontoxic. The mechanism by which RRVs induce cytotoxicity in experimental models is believed to mirror the pathomechanism of APOL1-mediated kidney disease. Therefore, elucidation of the mechanism of RRV-induced cytotoxicity is a major priority. Experimental models have failed to produce a unified mechanism that explains the multiple cytotoxic phenotypes caused by RRVs. Prior studies show that in a planar lipid bilayer, APOL1 protein forms a cation-selective pore that is permeable to Na⁺ and K⁺. In a HEK cellular model with inducible expression of APOL1 G0, G1, or G2, APOL1 also forms cation pores in the plasma membrane of mammalian cells, but only G1 and G2 cause aberrant influx of Na⁺ and efflux of K⁺, leading to cellular swelling, activation of JNK and p38 MAPK, and cellular death. Based on these results, we proposed that the cation pore function of RRVs is the proximal driver of cytotoxicity. While other investigators have confirmed our observation that RRVs cause K⁺ efflux and Na