Zinc enhances the phosphorylation of S6 kinase (S6 K) by mTORC1 through inhibiting protein phosphatase 2 (PP2 A), a phosphatase that dephosphorylates S6 K. The activity of PP2 A is increased in zinc deficiency [229, 230]. The gene discussed is XPNPEP2; the disease is Zinc deficiency.