CD34 and neoplasm: However, expressions of angiogenesis-related genes such as HIF1α, VEGF, CD34 and tumor invasion-related genes like MMP2, MMP9, E-cadherin and β-catenin were increased by either carbon ion beam or X-ray combined with gemcitabine compared to carbon ion beam or X-ray irradiation alone, implying that either high or low LET radiation may enhance tumor angiogenesis and/or invasion when combined with chemotherapy [52].