MMP2 and tuberous sclerosis: The homeostasis of the biological properties of lipid raft membranes by facilitating synthesis of sphingolipids was tightly regulated by PI3K-Rac1-Akt-regulated GLUT-1-mediated glycolytic metabolism, as evidenced by decreased Akt (Ser 473) phosphorylation and Rac1 activation together with heightened level of lipid raft membrane ceramide, decreased sphingolipid, cholesterol, and GLUT-1 levels in the lipid raft membranes, loss of glucose and GCS activity, and reduced MMP-2/-9 expression and invasive activity in TSC cells treated with LY294002.