HDAC9 and cancer: To test the functionality of the CARD software in improving primary screen hit selection, we first analysed two genome-scale siRNA studies for which secondary validation data sets were available: a screen for sensitization of cancer cells to histone deacetylase (HDAC)-inhibitor (vorinostat)-induced cell death17 and a screen to identify the human genes responsible for mediating repression of human papilloma virus (HPV) oncogenes28.