Maturation Promoting Factor or
M-Phase Promoting Factor (MPF)

MPF is activated when full-grown Xenopus laevis oocytes are stimulated with progesterone. Below is a model showing the pathway leading to the activation of MPF. This is only our model and should not be taken as gospel!

Fig. 1 During meiotic prophase arrest, high levels of cAMP and PKA activity within the oocyte promote the carboxylmethylation and activation of PP2A. Active PP2A promotes wee1 and mik1 activity which phosphorylate T14 and Y15 on cdc2 keeping Pre-MPF inactive.

Fig. 2 Progesterone causes a decrease in cAMP/PKA levels. c-mos mRNA is polyadenylated and translated into c-mos which leads to the phosphorylation and activation of cdc25. Active cdc25 removes phosphates on T14 and Y15. Lower cAMP/PKA also leads to the demethylation and inactivation of PP2A.