GRP and small cell lung carcinoma: Previous studies have shown that substance-P analogues reversibly inhibit ERK activation by neuropeptides in Swiss 3T3 cells; however, our studies suggest that in rat-1 fibroblasts and in human small-cell lung carcinoma cells (SCLC), in the absence of bombesin, substance-P analogues can activate ERK and c-jun kinase (JNK) in a GRP receptor-dependent manner (MacKinnon et al, 2001).