EVENT COUNTER MINIMA. “An intracellular counting mechanism must be present. These data included: 1) the Phase III Phenomenon itself; 2) our observation that cryogenically preserved cells “remember” at what doubling level they were preserved; and 3) the enormous literature describing hundreds of biological changes occurring in normal cells well before they lose their replicative capacity.”
http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html