Fig. (3) HDAC2 cytoplasmic sequestration parallels in vitro keratinocyte terminal differentiation. (A) Undifferentiated primary cultures of human foreskin keratincotyes (HFK) were either maintained in serum free keratinocyte medium (KSFM) or grown in KSFM medium containing 10% nFBS for 72 hours to initiate differentiation. Undifferentiated HFKs maintain strong nuclear HDAC2 localization, low keratin-10 expression, and uncondensed DNA. Terminally differentiating HFK cells display flattened morphology, cytoplasmic HDAC2, nuclear condensation and DNA fragmentation. Magnifications for both undifferentiated and differentiated cells are identical as keratinocyte differentiation results in cell flattening giving the false appearance of higher magnification. (B) Four day treatment with 2mM valproic acid reduces HDAC2 protein levels and increases expression of the differentiation marker Keratin-10 protein levels in HFK cells. Anti-tubulin serves as a loading control.