However, rat INS1 832/13 cell lines had a greater sensitivity to GIP (EC50 = 0.99 nM) than both primary mouse adipocytes and Neuro-2a neuroblastoma cells, and notably, pre-treatment with GIP (1 μM) for 24 h resulted in dramatically elevated basal cAMP levels that did not further respond to the subsequent GIP stimulation (Fig. 7h). The gene discussed is GIP; the disease is neuroblastoma.