CDK4 and cancer: Using a KEGG analysis, we further explored proteoglycans related to cancer (MAPK14, DDX5, STAT3, EGFR, PXN, GRB2, CBL) and various pathways, including mitogen‐activated protein kinase (MAPK) signalling (MAPK14, DUSP3, EGFR, GRB2), FoxO signalling (MAPK14, STAT3, EGFR, GRB2) and phosphatidylinositol‐4,5‐bisphosphate 3‐kinase (PI3K)‐Akt signalling (CDK4, EGFR, GRB2, LAMA5).