KDR and melanoma: Possibly, the astonishing upregulation of VEGFR2 observed in A375 and SK-MEL-28 melanoma cells in our experimental conditions may be considered as an adaptive strategy activated by vitamin D, in which increased availability of VEGFR2 on the melanoma cell surface potentiates the response to its inhibitor, cediranib, or elevated expression of the receptor is a response to inhibition of the downstream signaling from the receptor.