PtdIns(3,4,5)P3 3-methylenephosphonate, diC8 (3C-PtdIns(3,4,5)P3, diC8) is a synthetic PI(3,4,5)P3 analog in which the 3-phosphate bond has been rendered metabolically stable as a methylenephosphonate. P-3C908 increases sodium transport across monolayers of cells A6 through activation of GLUT4.