Since down-regulation of EGF in TC-1 tumors from fat-1 mice was predicted to promote TC-1 cell proliferation but tumor size in fat-1 mice was significantly smaller than in wild-type controls, we hypothesize that differences in MMP production between fat-1 and wild type mice may be responsible for the suppression of TC-1 tumor growth. The gene discussed is EGF; the disease is neoplasm.