HMOX1 and neoplasm: To clarify the effect of HO-1 expression on the survival and growth of the tumor cells, we established HO-1 over-expressed C26 cells (V8971) as well as HO-1 knock-down C26 cells (6708), which a 1.8-fold increased HO-1 expression, and an 80% decrease in HO-1 expression were achieved, respectively, compared to the vehicle C26 cells (3NC) (Figure 4A).