Fig. 1. (A) Strategy of Engrailed chromatin immunoprecipitation, cloning procedure and design of the probes used on Southern blot to test the specificity of the procedure. The En probe corresponds to the chromatin preparation used to construct the library. (B) Southern blots performed on 14 inserts isolated from the library. Clone inserts, visualized with ethidium bromide (EtBr), have been transferred onto nitrocellulose. Blots have been hybridized with EN probe and with Background probe, as indicated and described in A.