Classical Southern blot analysis. Human genomic DNA was digested by Xba I (X), HindIII (H), Pst I (P),BamHI (B) and EcoRI (E). Successive hybridizations were performed with PAR-1, PAR-2, and PAR-3 probes. The fragment size is given in kilobases below each lane. Whatever the enzyme used, a single cross-hybridizing fragment was seen for the three probes. For thePst I digest, PAR-1 hybridized with two fragments because of the presence of a Pst I site in the PAR-1 coding sequence.