How to choose the right buffer for my western blotting? - (Apr/20/2008 )

Hi All,
I will do western blotting for total and phosphorylated Erk-1/2 in a cell line. The protein is located in the cytoplasm but when it is activated it goes to nucleus. Would you recommend me to use RIPA buffer or cell lysis buffer? Many thanks in advance. Any help will be appreciated.

Either should be fine, just don't forget the protease and phosphatase inhibitors.