To overcome such resistances in non-mesenchymal tumor cells and identify potential sensitizers, three inhibitors of the histone deacetylase 6 (HDAC6)—Tubacin, CAY10603, and Tubastatin A were identified by the epigenetic compound library screening, which dramatically induce synthetic-lethal death under the cysteine-depleted condition (Fig. 1A,B). The gene discussed is HDAC6; the disease is neoplasm.