TSA cooperates with ATRA to induce transcriptional activity of a βRARE in ATRA-resistant cell lines harboring point mutations in the LBD of PML/RARα.

Relative CAT activity of ATRA-sensitive NB4 and ATRA-resistant NB4-MRA1, NB4-MR4, and UF-1 APL cells without (control) or with indicated concentrations of ATRA or 200 nM TSA is shown. A DR5-tk-CAT reporter was cotransfected with a β-galactosidase expression vector into the cells for normalization of the transfection. Each data point represents the mean of at least 3 independent transfections, and bars denote SD.