Fig. 1.

Linearity of the reverse transcriptase-polymerase chain reaction (RT-PCR) using different amounts of starting total RNA, 1 μg (a) 5 μg (b) or 15 μg (c), for the RT reaction. For the PCR amplification 1/50th of the product of RT was used. The data shown correspond to the amplification of a message that is abundant, such as β-actin, and therefore is likely to become limiting sooner than rarer messages. The proportionality on the starting amount of cDNA is detectable both in ethidium bromide-stained gel (A) and by specific hybridization (B). ϕX174 DNA digested with Hae III was used as size marker (M).