COL6A1 and breast cancer: APOC1+APOE+ metastatic macrophages also express COL6A1 and COL6A2, which are independent predictors of poor prognosis and indicators of distant metastasis in pancreatic cancer,[38] are associated with myofibroblast differentiation, matrix reorganization, and collagen deposition in breast cancer by interacting with myofibroblast cells via ITGA11.[42] In addition, COL6A1 and COL6A2 can interact with epithelial cells via SDC4 to activate cell adhesion and migration (Figure 6e,f).