Figure 3.

Mechanisms by which mesenchymal stem cells may become oncogenic after incorporation of a transgene. (A) Incorporation of an immortalizing transgene may result in the loss of normal cell-cycle checkpoints, karyotypic instability, or other changes which cause uninhibited proliferation of cells. (B) Insertional mutagenesis may disrupt a critical regulatory locus, resulting in dysfunction of the normal mechanisms of tumor suppression.