The mechanism of action of cisplatin as a chemotherapeutic agent has been attributed to DNA binding, while its mechanism of action as a nephrotoxin is unresolved. Only about 1% of intracellular cisplatin interacts with DNA, primarily forming intrastrand crosslink adducts, and many studies have implicated both nuclear and cytoplasmic causes of cisplatin-induced death in cultured cells. We have demonstrated that cisplatin cytotoxicity depends on cdk2 activity, which is at least partly through the cdk2-E2F1 pathway. The mechanism of the dependency on cdk2, and whether cdk2 activation of E2F1 represents the only cell death pathway involved is still unclear. Our previous work showed that deletion of the nuclear localization signal from p21^WAF1/CIP1, a cdk2 inhibitor, did not alter its protective action against cisplatin cytotoxicity. Active cdk2-cyclin complexes are localized in both nucleus and cytoplasm and it was reported that cdk2 translocated to the cytoplasm after an apoptotic stimulus. Herein, we show that cisplatin caused cell death in enucleated mouse kidney proximal tubule cells (TKPTS), which was prevented by cdk2 inhibition. Also, we localized cytoplasmic cdk2 to both the ER and Golgi compartments, and ER stress was blocked by specific cdk2 inhibition. We conclude that cisplatin can induce nuclear independent apoptosis, that cisplatin cytotoxicity can be initiated by cytoplasmic events, and that cytoplasmic cdk2 plays an important role in apoptosis signaling.