A fluorescent histone deacetylase (HDAC) inhibitor for cellular imaging

Fluorescence microscopy studies using 4-morpholinoscriptaid (4MS) demonstrated rapid cellular uptake of this scriptaid analogue into the cytoplasm but no nuclear penetration. As 4MS and scriptaid have the same in vitro activity against HDACs and KASUMI-1 cells; 4MS exemplifies a rational approach to subtly modify ‘profluorogenic’ substrates for intracellular studies.