COL15A1 and neoplasm: This hypothesis is based on observations of the presence of the ColXV gene in a tumour suppressor locus in the mouse and human genome, and on cell studies showing that the deletion of a chromosome 4 locus containing Col15a1 in mouse fibroblasts results in a malignancy of tumour cell hybrids and compromises the formation of collagenous tumour stroma [22,23].