Problem with trypsinising my 293Ts - (Jan/30/2012 )

I have been trypsinising my 293Ts for last 2 and a half years and now we are using commercial trypsin (.25%). And my cells form clumps or are lots of them dead. I never had such problem. I thwaed 4 different batches of the cells nad I am sure it is something to do with the trypsin. I am even using 1:10 diluted trypsin but now they are not as much as dead but are clumped and they do adhere but not growing fast as the yd ogrow like weeds.
Plz help.
Thank you so much

if trypsin is culprit, try trypsin from different source.

usually, i have this clumping, if cells are high passage number

Over-treating the cells with trypsin can cause clumping. Make sure you are only leaving the trypsin on until the cells are starting to lift off, not for a defined time.