KDR and renal cell carcinoma: Indeed, in multiple renal cell carcinoma (RCC) tumor models, the PERK inhibitor HC-5404 was reported to significantly enhance the antiangiogenic effect of standard VEGF receptor tyrosine kinase inhibitors (VEGFR-TKIs), such as axitinib and lenvatinib, inhibiting the formation of both new and mature tumor blood vessels [142].