CD31/PAS double staining was used to identify VM in tumors, a method that has been used in many studies.3,18,19 As shown in Table 2, among the 65 CRC samples, 10 exhibited the formation of vascular-like networks that were CD31 negative and PAS positive and contained red blood cells (Figure 1C). The gene discussed is PECAM1; the disease is colorectal carcinoma.