SMPD2 and glioblastoma: Although the action of 1α,25(OH)2VD3 has been implicated in different pathophysiological conditions [36,37,38] and its action via nSMase and aSMase has been described [17,18,19], its function and its involvement in aSMase and nSMase gene and protein expression in GBM cells have not been investigated yet.