Controls, as determined by a previous study [24], were added to ensure accurate interpretation of results: demonstrating (I) colonic origin – the HERV-H positive control was solely expressed in colon tissue (both normal and tumorous), whereas the expression of the HERV-H negative control was restricted to testicular cancer (positive control: 1900007_h_L5U3 and negative control: 1900006_h_env) and (II) tumorous origin (matrix metalloproteinase (MMP7) and osteopontin (OPN)) of the tissue. The gene discussed is SPP1; the disease is testicular cancer.