PS48 is an activator of PDK1 with an AC₅₀ of 8 μM. IC50 & Target: AC50: 8 μM (PDK1)^[1] In Vitro: PS48 activates full length PDK1 (His-PDK1- FL) and PDK1 50-359[Tyr288Gly;Gln292Ala] (His-PDK1 dm) with AC₅₀s (the concentrations required to reach 50% of the maximal activation) of 7.95±0.2 and 10.0±2.0 μM, respectively. PS48 binds to PDK150–359 with a 1:1 stoichiometry and a binding affinity in the micromolar range (K_d=10.3 μM)^[1]. PDK1 activator, PS48, has the ability to reverse the cell proliferation inhibition role of triptolide (TP) in vitro. The inhibition role of TP in cell number is significantly reversed by PS48. TP significantly increases the cell proportion in G0-G1 phase and decreases the cell proportion in G2-M and S phase. However, the effect of TP on cell cycle distribution is all reversed by PS48. In addition, suppression of PDK1/Akt/mTOR pathway by TP in high glucose (HG)-treated human renal mesangial cells (HRMCs) is also reversed by PS48, as well as the expression of Ki-67 and proliferating cell nuclear antigen (PCNA)^[2].