The phosphorylation mediates activation of tyrosine kinase SHP2. Expression of AXL receptor tyrosine kinase is a negative prognostic factor. CD135 is a Class III receptor tyrosine kinase. Protein Phosphatase-1 (PP-1), and Fyn tyrosine kinase. Its antiviral activity requires phosphorylation by the HCMV protein kinase, pUL97. Fostamatinib blocks the activity of the enzyme spleen tyrosine kinase (SYK). Honokiol inhibits phosphorylation of Akt, p44/42 mitogen-activated protein kinase (MAPK), and src. This causes activation of the Syk tyrosine kinase, causing it to phosphorylate. Efforts to use tyrosine kinase inhibitors in AML continue. PKB also phosphorylates glycogen synthase kinase (GSK), thereby inactivating this enzyme. It belongs to the large class of tyrosine kinase receptors. This phosphorylation is done by myosin light chain (MLC) kinase. MAPK phosphorylates 40S ribosomal protein S6 kinase (RSK). PKB then phosphorylates several target proteins, including glycogen synthase kinase 3 (GSK-3). Some phosphorylation of p70 S6 kinase was discovered.