Figure 6.

Signaling pathways activated by the LH surge in ovulatory follicles. LH activates multiple signaling pathways, including protein kinase A (PKA), protein kinase C (PKC), phosphatidylinositol 3-kinase (PI3K), and p38MAPK. LH also activates the epidermal growth factor receptor (EGFR) signaling pathway through the rapid induction of EGF-like factor expression and shedding of existing EGF-like factors from the membrane. Bold arrows emphasize the importance of PKA and EGFR signaling pathways in granulosa cells of ovulatory follicles. AC, adenylyl cyclase; AKT, Akt/protein kinase B; CREB, cAMP response element binding protein; DAG, 1,2-diacylglycerol; IP₃, inositol 1,4,5-triphosphate; MEK, mitogen-activated protein kinase kinase; MMP, matrix metalloproteinase; PIP₂, phosphatidylinositol 4,5-bisphosphate; PIP₃, phosphatidylinositol 3,4,5-trisphosphate; PLC, phospholipase C.