ALK and neuroblastoma: To evaluate potential synergistic effects of the telomerase substrate nucleoside precursor 6-thio-dG with other compounds that are active in neuroblastoma (the genotoxic drugs etoposide and doxorubicin, and the ALK inhibitor ceritinib), we assessed the effect of these compounds on cell viability individually and in combinations in eight neuroblastoma cell lines in vitro (CLB-GA, BE(2)-C, SH-SY5Y, KELLY, GI-MEN, TR-14, IMR-32 and LS).