MAPK3 and leukemia: The results showed that the inhibition of FGFR1 and AKT, not ERK1/2, significantly reduced FGFR1 activation-induced ERG expression in 293T cells (Figure 4G) and leukemia cells (Figure 4H), suggesting that FGFR1 upregulates ERG expression by activating PI3K/AKT signaling.