Figure 4.

TβR-I and TβR-II mRNA expression in human breast cell lines. Reverse transcription was performed using 2 μg total RNA. Primers for PCR were designed according to GenBank accession numbers: L11695 (TβR-I), L07594 (TβR-II), and M26434 (HPRT). Optimal annealing temperature (T _a) and the linear range of amplification were determined empirically for each set of PCR primers. PCR products were analyzed on 10% polyacrylamide gels and the intensity of ethidium bromide staining of PCR fragments was determined using a digital imaging system.