Abstract： Objective To compare the mesothelin expressions in 3 human pancreatic cancer cell lines between in vitro and in vivo and the developing speed among the subcutaneous tumors implanted with the 3 human pancreatic cancer cell lines in nude mice.Methods The human pancreatic cancer cell lines ( SW1990,BxPC3 and PANC1 ) were cultured and then were implanted subcutaneously into left axillas of nude mice.The volumes of these subcutaneous tumors were recorded every week to estimate their developing speed.The mice implanted with SW1990 and BxPC3 cells were observed for three weeks,while the mice implanted with PANC1 cell were observed for five weeks.The Western blot method was used to measure the expressions of mesothelin in the 3 kinds of cells and subcutaneous tumors,while immunohistochemical staining was applied to determine the expressions of mesothelin in 3 kinds of subcutaneous tumors.Results The sequence of quantities of expressions of mesothelin in these cell lines in vitro were BxPC3 ＞ PANC1 ＞ SW1990,and the sequence of quantities of expressions in vivo were SW1990 ＞ BxPC3 ＞ PANC1.One handrued percent of the tumors grew out successfully,and the sequence of speeds of their growth was SW1990 ＞ BxPC3 ＞ PANC1.Conclusions The mesothelin expressions among 3 kinds of pancreatic cancer cell line are different.The developing speeds of tumors originated from different subcutaneous tumors in nude mice are also different,and there is no association between them.