CASP3 and chronic obstructive pulmonary disease: Among the predicted potential targets, AKT1, IL6, TNF, TP53, MMP9, CASP3 and ALB had high frequency, and they were involved in several biological processes, including positive regulation of MAPK cascade, positive regulation of cell motility, response to oxidative stress, regulation of inflammatory response, which were closely related to the pathogenesis of COPD.