Figure 4.

STAT3 activity is required for regulation of MYCN expression by ALK. Neuroblastoma cell lines CLB-GE (A), CLB-BAR (B), Kelly (C) and CLB-GA (D) were starved and treated with either 250 nm crizotinib (24 h), 5 μm FLLL32 (8 h), 5 μm STATTIC (8 h), or control, as indicated. After cell lysis, samples were immunoblotted with antibodies against p-ALK^Y1278, MYCN, p-STAT3^Y705, and p-ERK. Pan-ERK, ALK and STAT3 antibodies were employed as loading controls. Three independent experiments with similar results were performed, and representative blots are shown.