Figure 3 – GH signal transduction through STAT, MAPK, IRS-1 and PKC. GH binding initiates the phosphorylation of JAK2 which in turn leads to phosphorylation of STAT molecules, activation of the MAPK cascade and activation of IRS-1. STAT5a and STAT5b homo/heterodimerise and translocate to the nucleuswhich, in turn,activates the PI3K and MAPK pathways.