Forkhead Box ml （ Foxml ） is a component of the Fox transcription factor family. It is only detected in proliferating ceils, but disappears when cells enter into their terminal differentiation phase. Foxml is closely related to cellular growth mainly through inhibiting cyclin-dependent kinase（cdk） inhibitors to influence cell proliferation. It also participates in growth hormone mediated cell multiplication. The overexpression of Foxml has been observed in many tumor cell lines and malignant tumors, indicating that Foxml might be an essential proto-oncogene in carcinoaenesis. Upregulation of Foxml is sufficient to induce genomic instability due to loss of heterozygosity and variation of copy numbers. Foxml-induced genomic instability was significantly enhanced and accumulated with increasing cell passages. Foxml might become a new potential target for the treatment human cancer based on future investigations.