Modulation of posttranscriptional and posttranslational regulatory processes by histone deacetylase inhibitors Acetylation is a very critical posttranslational modification in vivo. Targeting lysine residues of various proteins crucially modulates protein functions and interactions. The inhibitors of histone deacetylases are promising anticancer drugs currently in clinical testing. We could show that the treatment of cells with these histone deacetylase inhibitors is able to modulate cell fate by enhancing conditions that trigger apoptosis by two distinct mechanisms. Firstly VPA and co treatment with the chemotherapeutic agent HU induce expression of the pro apoptotic BH3 only protein BIM. The enhanced BIM expression arises from an increase in transcription of the BIM gene in an AP1 dependent manner. This effect occurs in cultured cells and in primary head and neck cancer cells from patients. We observed that the effect of apoptosis induction following treatment is mainly dependent on the level of BIM protein.