Label-free global phosphoproteomics experiment using PI3K-AKT-mTOR-S6K and RAF-MEK-ERK-RSK pathway activation and inhibition

The signaling network of skeletal muscle cells is controlled by a variety of protein kinases. Although many kinases are known players, their downstream targets are still largely unexplored. To gain further knowledge about the PI3K-AKT-mTOR-S6K and the RAF-MEK-ERK-RSK signaling networks in myotubes, we analyzed changes in protein phosphorylation levels upon pathway activation and direct kinase inhibition on a global scale. Based on the phosphoproteomics data, we further examined target relationships of the basophilic kinases AKT, RSK and S6K, which share the substrate recognition motif RxRxxp[ST].