Coupling of TPα to Gαs in 4-methylnitrosamino-1–3-pyridyl-1-butanone induced lung cancer stimulates PKA/CREB activation [63], resulting in expression/activation of the orphan nuclear receptor Nurr1, which stimulated proliferation of human lung cancer cells but could also be implicated in differentiation and apoptosis [63,64]. Here, NR4A2 is linked to lung carcinoma.