Representative autoradiograph of the primer extension analysis of MEL cells RNA.

Cells underwent erythroid differentiation induction, and were transfected with β5 (lane 2), β15 (TGG→TAG) (lane 3), β15 (TGG→TAA) (lane 4), β15 (TGG→TGA) ApaLI-positive at codon 2 (lane 5), β17 (lane 6), β26 (lane 7), or normal (lane 8) β-globin genes. Lane 1 contains 250 ng human reticulocyte RNA. Experiment was carried out as described in “Materials and methods” and Figure 1. The position and length of human β- and mouse α-globin cDNA are indicated on the right. Levels of human β-globin mRNA (hβ) relative to endogenous mouse α-globin mRNA (mα) are indicated at the bottom.