This project aims to systematically identify E3 ubiquitin ligases interacting with transcription factor FOXJ1 and M2 protein. Three experimental strategies were employed: (1) Co-transfection of FOXJ1-Flag and M2-myc in HEK293 cells, immunoprecipitated with IgG and myc antibodies; (2) Co-transfection of FOXJ1-Flag and M2-myc in HEK293T cells, immunoprecipitated with Flag antibody; (3) Overexpression of M2-myc in primary epithelial cells cultured under air-liquid interface differentiation, immunoprecipitated with IgG and myc antibodies.