HDAC6 and myeloproliferative disorder: Since there is a dispute regarding whether MPN cells depend on the class IIb deacetylase HDAC6,16 we treated HEL and SET-2 cells with the HDAC6 inhibitor marbostat-100.23 Marbostat-100 induced hyperacetylation of the HDAC6 target tubulin but not apoptosis (Supplementary Fig. 2f–i).