Heat shock factors (HSFs) regulate genes that protect cells from stress. This experiment studied the effect of the anti-inflammatory drug indomethacin on HSF1 and HSF2 in HeLa cells. Cells were treated with various concentrations of indomethacin and subjected to heat shock or normal temperatures. Nuclear extracts containing HSFs bound to radiolabeled DNA were run on a gel. The gel image shows that heat shock increased HSF binding (Band B) and indomethacin decreased HSF1 and HSF2 binding in a dose dependent manner (Band C). Antibodies added showed this effect was on HSF binding rather than expression levels.