NOTCH1 and lung adenocarcinoma: The same group also reported that treatment with γ-secretase inhibitor, MRK-003, specifically induced lung adenocarcinoma cell apoptosis (A549 and H1755 cells) under the condition of hypoxia (1% O2), but not normoxia (21% O2) [16], suggesting that the biological role of NOTCH1 in lung adenocarcinoma cells may be dependent on the concentration of oxygen and that the pharmacological inhibition of NOTCH1 may be useful for treating hypoxia-induced and NOTCH1-driven lung tumor cell growth.