mRNA standards

[Peter Agron]

    I am interested in comparing mRNA levels between promastigotes and
amastigotes and would like to solicit any opinions on what are accepted
mRNAs that would be appropriate internal controls for such experiments,
i.e. genes that are  expressed at the same level in the different cell
types.  Is actin acceptable, or is it necessary to use rRNA or some other
RNA?  Any information would be greatly appreciated.

    Thank you,
 
    Peter Agron
    San Francisco, USA