Honokiol (Figure 1), a polyphenol present in Magnolia grandiflora, was found to upregulate the expression of miR-34a, which in turn targets and inhibits the Wnt-1-Metastasis-associated protein (MTA)1-β-catenin pathway (Table 1), thus counteracting oncogenic effects of leptin on breast cancer growth and metastatic properties of human breast cancer cell lines MCF7, MDA-MB-231, MDA-MB-468 and T47D [79]. This evidence concerns the gene MTA1 and breast carcinoma.