RPS6KB1 and Insulin resistance: Additionally, p70 S6K-deficient mice had lower ser307 and ser636/639 phosphorylation of IRS-1 and remained sensitive to insulin longer when fed a high-fat diet in comparison to their controls, suggesting that p70 S6K is involved in ser307 and ser636/639 phosphorylation of IRS-1 and the induction of insulin resistance [26].