Protein knockdown method? - (Feb/07/2015 )

I performed siRNA transfection on cells monitoring mRNA expression, how would I relate this to determining a change in protein expression?

Is it only through Western Blotting, there's no way I can tell if mRNA levels affected protein expression?

WB is the standard, you could also use immunocytochemistry or any other discriminatory protein detection method.  WB is semi-quantitative (given the right conditions fully quantitative) and quick and cheap which are the main advantages.