MATERIALS AND METHODS

Mice Animal care and treatment was performed in accordance with the guidelines of the animal use and care committee of Japanese Foundation for Cancer Research, and conformed to the NIH ‘Guide for the Care and Use of Laboratory Animals’. All procedures were approved by the above committee. Seven-to-nine week old female nude mice (BALB/C nu/nu) were purchased from Charles River Japan, Inc. The mice were maintained in the laboratory for animal experimentation in a Specific Pathogen Free environment. Cell Lines The human colon and stomach cancer cell lines used in this study were HT-29, WiDr, HCT-116, HCT-15, HCC-2998, MKN7, MKN28, MKN45, MKN74 and St-4 and have been described elsewhere. 18, 19) These cells were maintained as monolayer cultures in RPMI-1640 medium supplemented with 5% fetal calf serum (FBS) and glutamine.