However, for the lung cancer cell lines NCI-H661 and NCI-H640, the glioblastoma cell line GaMG and the prostate cancer cell line PC3, PAX6 knockdown by siRNA resulted in an increased Dkk3 expression, indicating that endogenous PAX6 repressed Dkk3 expression in these cancer cell lines. The gene discussed is DKK3; the disease is glioblastoma.