Fig. 2

Protein interaction analysis in biological systems. (a) Protein–Protein Interaction (PPI) Networks visualization. (b) Venn diagram of the key genes identified by four algorithms. (c) Hub genes screening using the Support Vector Machine (SVM) algorithm. (d− 1) Lasso coefficient path results. (d− 2) Cross-validation curve results. (e) Candidate biomarkers identified by two machine learning algorithms. (f) Expression distribution of 6 candidate biomarkers in the training and validation sets. (g) Spearman correlation analysis of the 3 biomarkers in the validation set.