Growth curve for PC3 cell line - (May/10/2011 )

Hi
I am doing a growth curve in 24 well plate starting with 5000 cell/ml in each well and counting very 2 days for 12 day since the PC3 cell are cancer cell so the growth curve should be sigmoidal since they usually don't die but I have reached day 10 and they are still growing in very high rate so I could not see the day where they have maximum growth yet what did I do wrong ?????

Cancer cells often don't have contact inhibition, and consequently will not stop dividing even when they have reached confluence. You may not be able to get a true sigmoidal curve.