The aim of our study was to investigate the target relationship between miR-143 and mitogen-activated protein kinase 1 (MAPK1) and explore the effect of miR-143 on the endometrial cancers (EC) cells through targeting MAPK1. We collected EC tissues and adjacent tissues, and transfected miR-143 mimics and MAPK1 siRNA into EC cells with lipofectamine. The gene discussed is MAPK1; the disease is endometrial cancer.