PECAM1 and neoplasm: Strong positive correlations were found between CD31 levels in primary tumor tissue and FABP4+MMP9+MMP2+TIMP1- (r = 0.82, p < 0.05) and FABP4+MMP9+MMP2-TIMP1- (r = 0.67, p < 0.05) populations of plasma sEVs (Figure 3A).