PPI network and the hub gene module of DEGs. (A) PPI network of DEGs was constructed with Cytoscape. Upregulated genes are marked in light red and downregulated genes in light blue. (B) Hub gene module obtained from the PPI network based on STRING with 8 nodes and 28 edges. (C) Hub genes and their co-expression genes were analyzed using cBioPortal. Nodes with bold black outlines represent the hub genes. Nodes with thin black outline represent the co-expression genes. PPI, protein-protein interaction; DEGs, differentially expressed genes; STRING, Search Tool for the Retrieval of Interacting Genes; CDC6, cell division cycle 6; CDK1, cyclin-dependent kinase 1; CDC45, cell division control protein 45; BUB1, budding uninhibited by benzimidazoles 1; MCM4, minichromosome maintenance complex component 4; TOP2A, DNA topoisomerase II α.