In order to study the neutrophil gelatinase-assiciated lipocalin(NGAL)gene expression character in the progress of malignant transformation of human immortalized esophageal epithelial cell, differentially expressed NGAL gene was identified by using cDNA microarray in the human immortalized esophageal epithelial cell line(SHEE) and malignant transformed esophageal cancer cell line(SHEEC). NGAL expression profile was further confirmed by Northern blot and RT-PCR. A cDNA encoding NGAL from SHEEC was amplified by PCR and sequenced. Alignment was analyzed by NCBI database. The results indicated that NGAL gene was overexpressed in the SHEEC. The coding region cDNA of NGAL from SHEEC was cloned and identified. Alignment of its deduced amino acid sequence compared to the mouse 24p3 protein, the rat neu-related lipocalin(NRL), the human NGAL from neutrophil and ovarian cancer demonstrated a very high degree of conservation. It can be concluded that NGAL overexpression possibly played an important role in the progress of malignant transformation of human immortalized esophageal epithelial cell. NGAL may be a new oncogene or promoter-tumor gene.