Mathematical model assuming inhibition of phosphatase activities during receptor activation. (A and B) Assumed deceleration of 4-phosphatase (4-Pase; A) and 5-phosphatase (5-Pase; B) during receptor activation (shaded area). (C–F) Simulated time course of PM PtdIns4P (C), PM PtdIns(4,5)P₂ (D), Ins(1,4,5)P₃ interacting with LIBRAvIII (E), and DAG interacting with C1A domains (F). Magnified traces underneath are expanded to reveal the tiny effects of phosphatase inhibition.