PECAM1 and neoplasm: Consistent with the increased stem cell features displayed by HOXA9-positive cells, our subcutaneous xenograft models using U87MG cells showed that HOXA9 accelerates tumor growth and tumor-related angiogenesis, with a concomitant increase in the expression of proteins involved in these cellular processes (Cyclin D1, Ki-67, BCL2, and PECAM1; Figure 4).