Expression rate of human epidermal growth factor receptor protein in colorectal cancer. A: The expression of HER-2 protein in moderately differentiated, weakly positive colorectal cancer tissue (IHC+, × 100); B: The expression of HER-2 protein in moderately differentiated, positive colorectal cancer tissue (IHC++, × 100); C: The expression of HER-2 protein in moderately differentiated, strongly positive colorectal cancer tissue (IHC+++, × 100). HER-2: Human epidermal growth factor receptor.