Key open questions include (i) whether ABL nuclear localization is important for restraining tumor cell growth on 3D matrix, as originally described for Abl’s ability to suppress cellular transformation (39), (ii) which functional domains of the Abl kinases are required for suppressor functions, and (iii) what are the specific roles of ABL vs ARG when they do function as suppressors of tumor progression and metastasis? The gene discussed is ABL2; the disease is neoplasm.