In additions, clusters 4, 7 and 10 expressed a variety of collagen proteins including COL1A1, COL1A2, COL3A1, COL6A1 and COL6A3 (Fig. 6e), which have been previously linked to abilities of proliferation, invasion, metastasis and drug resistance of tumor cells [50–53]. This evidence concerns the gene COL6A1 and neoplasm.