NAIL IN COFFIN TO HYPOTHESIS. “Cells aging in vitro do, indeed, acquire hundreds of incremental and decremental physiological changes as the approach the end of their in vitro lifespan. Yet, none of these changes raise the cell to a higher level of differentiation or specialization. To call the Phase III Phenomenon differentiation seems entirely inappropriate.”
http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html