a Western blot examining the COX1- and COX2-knockdown efficiency in A549 cells. b ALDH staining assay was performed to check ALDH + sub-population percentage in A549-shCtrl, shCOX cells with or without ibuprofen treatment. c Side-population assay was performed to detect SP percentage in A549-shCtrl, shCOX cells with or without ibuprofen treatment. d, e Statistic results of ALDH + subpopulation and side population are shown. f Western blot examining the expression of histone 3 modification markers, KDM6A, KDM6B and HDACs in A549-shCtrl, shCOX cells with or without ibuprofen treatment. g HDAC activity in A549-shCtrl, shCOX cells with or without ibuprofen treatment. h Western blot examining the expression of ICAM3 in A549-shCtrl, shCOX cells with or without ibuprofen treatment. All data shown are representative of three experiment repeats.