PIK3R1 and Glucose intolerance: However, glucose intolerance was evident in mice in which PI3K signaling in skeletal muscle was inhibited by muscle-specific disruption of Pik3r1 (which encodes the p85α, p55α, and p50α regulatory subunits of PI3K) together with whole-body disruption of Pik3r2 (which encodes the p85β regulatory subunit)15.