NRN1 and renal cell carcinoma: Because NRN1 activates transcription factor nuclear factor of activated T-cells (NFAT) c4 via the binding NRN1 to insulin receptor and the activation of calcium signaling-calmodulin-calcineurin axis in neuronal cells (19), NRN1 may also activate CXCR4 transcription by modulating some transcriptional machinery in RCC cells.