The luciferase gene reporter assays were performed in HEK293 cells. The Smp14 promoter-target sequence was cloned upstream of the luciferase reporter gene in the vector pGL4.23 (Smp14/3X-pGL4.23). This vector was co-transfected with the SmRXR1/SmNR1 heterodimer and/or co-transfected with SmCBP1 or SmGCN5 (A–H). The HDAC inhibitors NaB (5 mM) and TSA (2 µM) were tested (B). The dose-dependent transcriptional activation of the Smp14 promoter by SmCBP1 or SmGCN5 is shown (C and D). Small synthetic HAT inhibitors (2 µM) were tested in the transfected cells (E and F): PU139 (a), PU141 (b), SF7 (c), SF18 (d) and SF19 (e). Dose-dependent inhibition (0.5 nM, 1 µM and 2 µM) of SmCBP1 and SmGCN5 by the most potent inhibitor, PU139 (G and H). Results were plotted in relation to the firefly luciferase activity obtained from cells transfected with the Smp14/3X-pGL4.23 vector alone. Graphs are pooled from three independent experiments. Student's t-test was applied, with *p<0.05, **p<0,01, ***p<0.001 and ***p<0.001. Western blot data are representative of three independent experiments.