JUN and central nervous system cancer: Moreover, it has been reported that SP binds to NK-1R of U-373 MG glioma cells, producing: a rapid increase in the synthesis of IP3, an increase in the concentration of cytosolic Ca2+ and the induction of immediate early transcription of the expression of the c-Fos and c-Jun (activator protein 1 (AP-1), a transcription factor) genes, and an increase in DNA synthesis [45].