Cells have amazing features that allow them to guide their development paths and determine their individual and collective fates. Dedifferentia-tion and transdifferentiation (cell plasticity) are little-understood phenomena that allow cells to regress from an advanced differentiated state to a less differentiated one, including the case where cells lose their specific function and become stem cells. In this paper, we introduce cell plasticity into a class of mathematical models we are interested in. We explore a new model involving a dedifferentiation function in the case of two cell maturity stages (stem cells and progeny). We highlight the role that dedifferentiation may have in the survival of cancer cells during therapy. The latter hypothesis appears to be in line with some medical observations.