After treating the cells with metformin for 7 d, changes in the expression of >160 cancer- and metastasis-related gene transcripts were evaluated with the help of RNA arrays, of which 19 candidates, namely APC, BCL2L11, CASP8, CDH1, CDKN1A, CEACAM1, COL1A1, CTNNA1, IGF1, PTEN, RAC1, TGFB1, MMP2/9/10 and TIMP1/2/3/4, were selected for a follow-up quantitative real-time PCR (qPCR) analysis, including further treatment conditions. The gene discussed is TGFB1; the disease is cancer.