In addition, HE4 is a secreted glycoprotein encoded by whey acidic protein gene.[32] Under physiological conditions, it is mainly expressed in the respiratory system and reproductive system, and the expression level is related to age, smoking, and menstrual cycle.[32,33] Under the pathological conditions of malignant tumors, HE4 can induce EC cell proliferation and promote tumor cell metastasis and invasion by activating related carriers and signal pathways. This evidence concerns the gene WFDC2 and neoplasm.