In this study, while we observed that the species of the major collagens, such as Col I, Col II, Col III and Col V, remained unchanged (Figure 5b), certain collagen chains existing in normal breast ECM disappeared in breast tumor ECM (Figure 5b) and increased Col1a1 gene expression and protein levels were identified in breast tumors (Figure 5c,d). This evidence concerns the gene COL1A1 and breast neoplasm.