Figure 5: Network analysis of differentially expressed phosphoproteins in the Trend 2 group constructed using String and Cytoscape software.

CSNK2A1, also known as CK2, was added to analyze CK2-interacting phosphoproteins. (a) Further functional enrichment with DAVID online software revealed clusters of proteins connected to various biological functions and cellular components. (b) The first-neighborhood protein-protein interactions of CK2 were selected. Within the CK2 network, four proteins, HSP90AA1, NCL, LIG1 and HMGA1, have been reported to play roles in lung cancer and are marked with red circles. The various red color in the filled circle indicates the different ratios of the selected phosphorylation sites in PC9/gef cells and PC9 cells.