PTPN4 and lung cancer: Studies have found that the bromodomain inhibitor I-BET151 could reduce the expression of HOTAIR via affecting its promoter, thereby playing a role in tumor suppression.24 In addition, Kruer et al25 studied the mechanism of action of MEG3 and found that palbociclib treatment of A549 and SK-MES-1 lung cancer cells could activate the Rb pathway and increase the expression of MEG.