Specific Hdac1 inhibition with MGCD0103 impairs fin regeneration. (A) Western blot analysis for acetylation of histone H3 and histone H4 in 4 dpa fin regenerates treated with DMSO or 5 μM MGCD0103 starting from the time of amputation. The level of acetyl-H3 and acetyl-H4 in MGCD0103-treated fins was increased compared with DMSO-treated fins. β-actin and histone H3 were used as loading controls. (B-E) Whole caudal fins at 2 (B), 3 (C), 7 (D) and 10 dpa (E) treated with DMSO or 5 μM MGCD0103 starting from the time of amputation. MGCD0103 treatment for 10 days impaired regenerative growth without affecting the early stages of regeneration. Arrowheads indicate the amputation plane.