摘要Protein phosphatase 2A(PP2A)is a family of ser/threonine phosphatases com-posed of the core enzyme to which one of the variable regulatory B subunits(PP2A-B)is bound.PP2A is implicated in the regulation of numerous cell biological functions,including cell cycle,ampli-fication of DNA,signal transduction,cell differentiation and transformation.Recently,more evidence indicated that the abnormal expression of PP2A in relevance with tumorigenesis,so PP2A is identified as potential tumor-inhibiting factor.MicroRNAs are new mechanism involved in the development,progression and metastasis of tumor.The cell cycle is a complex and elaborate process involving nu-merous regulatory proteins as directors.Reversible phosphorylation of protein plays significant role in the process of cell cycle control.We discuss PP2A and miRNAs in xenobiotics carcinogenic process to the cell cycle control the important meaning in toxicology research.