PRL and cancer: Based on KEGG pathway enrichment analysis, 34 OSRGs were mainly enriched into pathways like nicotinate and nicotinamide metabolism, EGFR tyrosine kinase inhibitor resistance, Th1 and Th2 cell differentiation, prolactin signaling pathway, PD-L1 expression and PD-1 checkpoint pathway in cancer, and proteoglycans in cancer (Figure 2(c)).