To test whether LPP3 regulates tumor cell behavior, we knocked down LPP3 and investigated glioblastoma cell proliferation and tumor formation; conversely, we forced expression of LPP3 in LPP3-deficient human colon carcinoma (SW480) cells to address the hypothesis that LPP3 potentiates cell proliferation and tumor growth. The gene discussed is PLPP3; the disease is glioblastoma.