Next, we performed a more detailed analysis using Caki-1 cells (VHL wildtype) and 786-0 cells (VHL mutated), with HEK293 cells used as controls, and analyzed the response to carfilzomib in comparison to sunitinib, sorafenib and axitinib, which are VEGF receptor targeting receptor tyrosine kinase inhibitors (TKIs) approved for the treatment of metastatic RCC (Figure 3). Here, VHL is linked to renal cell carcinoma.