STAT3 and neuroblastoma: To test this hypothesis, U87-MG cells were incubated in the absence or presence of agonists of Gq-coupled receptors (bombesin, bradykinin, or histamine) for 24 h without serum, the conditioned media were then collected and applied to SK-N-SH neuroblastomas and SK-N-MC neuroepitheliomas for 15 min, and stimulatory phosphorylations of ERK as well as signal transducer and activator of transcription 3 (STAT3) in the recipient cells were assessed by Western blotting (Figure 4A).