GK444 (Compound 15a) is a HDAC1/2 inhibitor ( IC 50 : 100 and 92 nM for HDAC1/2 respectively). GK444 inhibits Caco-2 cells with IC 50 of 4.1 μM. GK444 also reduces TGF-β1 induced COL1A1 mRNA levels in primary normal human lung fibroblasts. GK444 inhibits Bleomycin -induced lung fibrosis in mice.