Protein kinase can be classified by substrates, including tyrosine kinase, serine threonine kinase, histidine kinase and cysteine kinase. Sometimes, protein kinase can be further subdivided into categories. For example, tyrosine kinase. Tyrosine kinase is very important. According to the tyrosine kinase whether exists in cell surface transmembrane, tyrosine kinase is primarily classified as receptor tyrosine kinase (RTK) and non-receptor tyrosine kinase (NRTK). RTK consists of EGFRs, PDGFRs, MCSFRs, IGF1R, INSR, NGFR, FGFRs, VEGFRs, and HGFR. NRTK consists of JAKs, FAKs, SRCs, ABLs, TECs, ACKs, CSKs, FESs, FRKs, and SYKs.