VHL and renal cell carcinoma: In long-term in vitro experiments, carfilzomib was found to be more potent in a RCC cell line with VHL-deficiency compared to a cell line harboring wildtype VHL. This cell-type-specific antitumoral activity of carfilzomib was found to correlate with the level of accumulation of ubiquitinated proteins, suggesting proteotoxic stress as the underlying mechanism.