MMP9 and esophageal squamous cell carcinoma: To further confirm the presence of LCN2/LOXL2/MMP9 ternary complexes in ESCC cells, co‐immunoprecipitation using whole cell lysate was performed after co‐transfection of LCN2‐HA/LOXL2‐Flag, LCN2‐HA/MMP9‐Flag, or LOXL2‐HA/MMP9‐Flag.