Knockdown of Hipk1 or Hipk2 results in changes in expression in related but nonidentical groups of genes. Total RNA was isolated from fetal liver erythroid cultures grown in Epo-containing media 36 hours after shRNA retroviral infection, and then reverse-transcribed, labeled, and hybridized onto Agilent mouse expression arrays. Each sample was isolated and processed in duplicate and compared with a luciferase control isolated during the same experiment. (A) Log₂ ratios for each knockdown culture compared with control are plotted: sample shHK1 (Hipk1-KD) is on the abscissa and shHK2 (Hipk2-KD) on the ordinate axis. Dashed lines indicate ratios of 2-fold increase (1) and 2-fold decrease (−1) in expression compared with control. Note the paucity of genes falling in the top right or bottom left corners. (B) Functional ontology classifications for significantly changed genes (both increased and decreased) in the Hipk2-knockdown cells; only significantly enriched categories are listed.