PTH1R and lung cancer: Since PTH1R stimulates cAMP as its second messenger in H1944 cells (Hastings et al. 2009) and BEN lung cancer cells (Hastings et al. 2004; Kukreja et al. 1988; Pizurki et al. 1988), we investigated the direct effects of cell-permeant cAMP compounds on H1944 cell growth.