DLX5 knockdown suppresses cell proliferation by inhibiting cell cycle progression. (A) lentiviruses harboring shRNA against LacZ or DLX5 were generated and used to infect DLX5-positive (IGR-OV1, OVCAR4, OVCAR8 and OVCAR10) or DLX5-negative (SKOV3 and A2780) ovarian cancer cell lines. Cell viability/proliferation was determined by WST-1 assay 5 days after viral infection. (B) Cell proliferation curves of IGR-OV1, OVCAR4 and OVCAR8 cell lines after virus infection at the indicated times. (C) Cell cycle analysis was performed on IGR-OV1, OVCAR4, and OVCAR8 cells with control or DLX5 knockdown. (D) Rates of DNA synthesis were determined by counting cells staining with BrdU. (E) DLX5 knockdown results in decreased expression of various cell cycle regulators, including cyclins A, B1, D2 and E1. (F) DLX5 knockdown reduces growth of xenografted OVCAR8 cells in SCID mice. Tumors were recovered 1 month after subcutaneous injection and weighted (* p<0.05).