Description: IC50 Value: 0.57 uM (For HDAC1,MTT assay) CI-994 (N-acetyldinaline) is a novel oral compound with a wide spectrum of antitumor activity in preclinical models, in vitro and in vivo. The mechanism of action may involve inhibition of histone deacetylation and cell cycle arrest[1]. in vitro: Different CI-994 concentrations were tested, ranging from 0.01 to 160 microM at 24, 48, and 72 h of treatment inA-549 (adenocarcinoma) and LX-1 (squamous cell carcinoma) ,with MTT assay. A concentration-dependent cell survival inhibition was observed, with an IC50 at 80 microM. The effect of CI-994, as demonstrated by recovery experiments, was cytostatic and seemed to be superimposable in both cell lines. Cytofluorimetric analysis to assess cell cycle perturbation and apoptosis was performed after 24 h of treatment, indicating a cell block with concomitant increase at G0/G1 phase, a reduction at S phase level at 20, 40, 80, and 160 microM, and apoptosis at the higher conce