Many stromal cells in tumor tissues including fibroblasts, neutrophils and macrophages were also positively stained for HO-1 (Figure 1i-l).More important, the localization of HO-1 was found significantly different in CRC with different histological differentiation; the majority of well differentiated cancer tissues showed significantly higher cytoplasmic expression of HO-1 than moderately and poorly differentiated tumors which nuclear HO-1 expression was more apparent (Figure 2). This evidence concerns the gene HMOX1 and cancer.