PECAM1 and neoplasm: Interestingly, a reduction in PFKP expression resulted in decreased blood vessel formation as evidenced by the intensity of CD31 expression (Fig. 1B), in which the tumor sizes at an early stage (day 5) were comparable between groups injected with control shRNA-expressing and PFKP shRNA-expressing LN229/EGFRvIII cells (Fig. 1A).