Fig. 2.

Production of two novel murine Med1 alleles. (A) The Δ1–3 and Δ2–5 constructs were prepared by replacing exons (black boxes) 1–3 and 2–5, respectively, with a pgk-neo cassette; thicker lines indicate the recombination arms. The Δ1–3 and Δ2–5 alleles were produced in ES cells after homologous recombination. In the wild-type allele, the SpeI (S) restriction sites are located 13 kb upstream and 11 kb downstream of exon 1, respectively. (B) Southern blot analysis of genomic DNA from MEF of different Med1 genotype. After SpeI digestion and hybridization with a 1.5-kb SacI-HindIII probe located 6 kb upstream of exon 1 (panel A), the wild-type, Δ1–3, and Δ2–5 alleles show a 24-, 13-, and 16-kb fragment, respectively. (C) The expression of Med1 was monitored by RT-PCR analysis of MEF RNA by using primers located in exons 1 and 3 (A). No expression was detected in homologous recombinant cells.