CDKN1B and neoplasm: In addition, our results in LLC WRC-256 tumor cells confirm the antiproliferative effect of metformin in another cell line and the effect of metformin in the control of cell cycle, since an increase in pRb mRNA (PRB1 gene), p53 mRNA (TP53 gene) and p27 mRNA (CDKN1B gene) was also observed in this cell line.