KDR and neoplasm: Presently, we consider sorafenib [30], a multi-RTKI with an IC50 for VEGFR2 > 100-fold higher than the IC50 values of the VEGFR-selective RTKIs axitinib (AG-013763), cediranib (AZD2171), and AG-028682 [31-34], all of which strongly inhibit metronomic CPA-induced anti-tumor immunity and tumor regression [10].