PTEN missense mutation that results in the substitution of serine at position 170 with glyciine affects the phosphatase domain of PTEN. Serine residue S170 is involved in the formation of intedomain hydrogen bonds between the phosphatase domain and the membrane-binding C2 domain (Lee et al. 1999). PTEN S170G (Ser170Gly) mutant has not been studied directly but is assumed to have impaired phosphoinositide phosphatase activity similar to other S170 substitution mutants of PTEN (Han et al. 2000).