Fig. 5. Change in Ser21 phosphorylation of glycogen synthase kinase 3 (GSK3) and phosphotyrosine (p-Tyr) proteins in human spermatozoa by 8-bromoadenosine 3′,5′-cyclic monophosphate (8-br-cAMP), H89, and Akt inhibitor VIII treatment. (A) Western blots of p-GSK3(Ser21) and p-Tyr proteins in human spermatozoa after incubation with 8-br-cAMP in Tyrode’s basal medium (TBM) or Tyrode’s complete medium (TCM). 8-brcAMP (1 mM) increased p-GSK3α(Ser21) and p-Tyr proteins levels, and which was apparent in the spermatozoa incubated in TCM compared to those incubated in TBM. (B) Western blots of p-GSK3α(Ser21) and p-Tyr proteins after incubation with the PKA inhibitor H89 in TCM. H89 (100 µM) markedly decreased the levels of p-GSK3α(Ser21) and p-Tyr proteins in human spermatozoa. (C) Western blots of p-GSK3α(Ser21) and p-Tyr proteins after incubation with Akt inhibitor VIII in TCM. Akt inhibitor VIII (50–100 µM) markedly decreased the levels of the p-GSK3α(Ser21) and p-Tyr proteins after incubation in TCM.