In the assessment of intra-tumor vessels, fibrin thrombus formation as identified by PTAH staining was not observed in the i-PDT-treated groups (A–C) but CD31 immunostaining gave the impression of a narrow vascular bed in the i-PDT-treated groups that was not observed in the control group (D, E) (Figure 3G,H). This evidence concerns the gene PECAM1 and neoplasm.