OVCAR8 cells were infected with or without HA-tagged wild-type CDK7 (WT) or C312S mutant (CS), followed by G418 selection to obtain stably transduced cells. The cells were pre-treated with doxycycline (200 ng/ml), and were then (A) seeded in 12 well plate and treated with THZ1 at 250 and 500 nM, with cell lysates prepared for immunoblotting after 6 hr of treatment. (B) seeded in 96-well plate and treated with increasing concentrations of THZ1 or YKL-1–116. Cells were subjected to CellTiter-Glow Luminescent Cell Viability Assay after 72 hr of treatment. Data were represented as mean ± SD of biological triplicates. (C) seeded in 12-well plate and treated with increasing concentrations of YKL-1–116 (0, 62.5, 125, 250, 500, 1000 nM) in duplicate, and subjected to clonogenic cell growth. Cells were fixed 7 days after seeding, and stained with crystal violet.