Fig. 5. MAPK4 enhances insulin and EGF-induced AKT phosphorylation/activation independent of PI3K.

a MDA-MB-231 and HS578T cells with Dox-inducible knockdown of MAPK4 (ishMAPK4) or control (iNT) were induced with 4 μg/ml Dox for 3 days. The cells were then plated in 6-well plates. Twenty hours later, the cells were serum-starved overnight followed by treatments with 100 nM insulin for the indicated time (minutes). The cell lysates were then prepared and used in western blots. b Western blots on SUM159-ishMAPK4 and -iNT cells that were similarly treated as described above. These cells were also pre-treated with Pictilisib or DMSO control for 2 h before 100 nM insulin stimulation. c Western blots on MDA-MB-231 and SUM159 cells with Dox-inducible knockdown of MAPK4 (ishMAPK4) or control (iNT) that were similarly treated as described above. These cells were pre-treated with PI3K inhibitors Pictilisib, Alpelisib, or control for 2 h followed by 200 ng/ml EGF stimulation for the indicated time. Data are representative of at least three independent experiments.