How do cells count ?!

Jan Ulrik Thorup thorup at BIOBASE.DK
Wed Jan 11 05:06:29 EST 1995

Dear netters. As far as I've understood, normal tissue cells divide a 
determined number of times (64 or so)  and then they die. Cancer cells 
and neoplastic cell-lines seem to have lost this "limitation of number of 
divisions" and could in theory divide indefinitely. So how do normal 
cells count the number of divisions they have been through ? Do they 
accumulate a "count-protein" that increases in amount/cell with 
increasing division-passage, modify some other (more or less) vital part 
of the cells machinery (allow DNA to be mutated, allow oxidation, allow 
free radicals ...) slowly as they grow older or is there some other 
mechanism. What is known about cells "counting" today ? And might that 
"counting-meter" be reset to zero or at least be halted ?


E-mail thorup at biobase.dk

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