CYB5R1 and colorectal carcinoma: In CRC, staining revealed a spectrum of CYB5R1 expression, ranging from negative in 31 cases (14%, score 0), through weak and moderate expression in 150 cases (68%, score 1) and 36 cases (16%, score 2), respectively, to strong expression in 4 cases (2%, score 3, Figure 1).