which RNA? which extraction method? which kit?
 

I'm working with HepG2 cells and want to extract RNA for both microchip gene expression analysis, and for follow up RT-PCR.
Should I extract total RNA or mRNA? (seems different kits used for each)
Should I use "RNA stability products" - advertised to maintain fidelity of gene expression?
And products people have used and are happy with? Biorad, Sigma, and Qiogen both seem to offer lots of different products/kits - feels overwhelming!!
thx!
:help: