Figure 5.

Disruption of the Jak1 binding proline-rich Box1 region of IL-4Rα abolishes the induction of Cɛ germline transcripts following homodimerization of the EpoR/IL-4Rα chimeric receptor . The cells transfected with empty pcDNA3 vector, EpoR/IL-4Rα Box1 deletion mutants (Box1 mut 1 or Box1 mut 2), or intact EpoR/IL-4Rα were left unstimulated (None), or stimulated with Epo (50 units/ml) or IL-4 (200 units/ml) for five days and assessed for induction of Cɛ germline transcripts and expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by Northern blot analysis. Similar results were obtained in two independent experiments.