The study on proteome of human cancer is helpful to explain its pathogenesis and make good effect on its prevention and cure. We compared the 2-DE maps of whole proteins of human lung cancer line A549 at 37 degrees C, 42 degrees C and 45 degrees C for the purpose of studying the expression of its heat shock proteins. Three temperature-sensitive differential spots were obtained and named as P1, P2, P3, respectively. Analyzed by MALDI-TOF-MS and Peptident software searched in the SWISS-PROT database, the three differential proteins were elementarily identified. P1 matches with two proteins belong to the Aldo-keto reductase family, P2 may be a new protein and P3 is Zinc finger protein 11A.