Figure 4.

Temporal perturbation of the Wnt signaling pathway modulates somatic cell reprogramming efficiency. The levels of Wnt pathway activation during somatic cell reprogramming need to be precisely modulated in order to reach complete reprogramming. Somatic cells showing low Wnt activity (Wnt OFF state) at early stages of reprogramming and activation of the Wnt pathway (Wnt ON state) at late reprogramming stages, respectively, will result in completely reprogrammed induced pluripotent stem cells (iPSCs). In contrast, somatic cells with Wnt ON at early reprogramming stages or Wnt OFF at late stages produce partial or non-reprogrammed cells. It has also been demonstrated that high or aberrant levels of activation of the Wnt pathway have an inhibitory effect on somatic cell reprogramming.