Fig. 5. Expression analysis of the human α- and β-globin genes. (A) Thirty micrograms of total RNA from K562, HeLa, 293 and RPMI 8420 cells were electrophoresed, blotted and hybridized using a human α-globin probe. Ribosomal RNA is shown as a loading control (rRNA). (B) For RT–PCR, 2 µg of total RNA from the same cells were incubated with (+) or without (–) reverse transcriptase and PCR amplified using primers complementary to the first and third exon of the α- or β-globin genes. A 10^–4 dilution of the K562 RNA was used to equal the PCR signal obtained for α-globin in HeLa and 293 cells. RT–PCR products were electrophoresed, blotted and hybridized to α- and β-globin-specific probes.