HDAC9 and neoplasm: Similar to our Drosophila models, inhibiting trametinib deacetylation by HDAC inhibitor (vorinostat) or via a competing substrate (phenacetin) also significantly suppressed trametinib resistance in mouse AKP tumour organoids; again, single agents had no effect in the absence of trametinib (Fig. 4e, f, Supplementary Fig. S3e, h).