Structural analysis of the human β-globin cluster–containing BAC. (A) BAC 4396-44 DNA was digested withNotI, SalI, or KpnI, and a Southern analysis was performed. The blot was hybridized sequentially with probes for HS-4 (lanes 1), ɛ (lanes 2), γ (lanes 3), β (lanes 4), and 3′HS-1 (lanes 5). The relevant lanes from each autoradiogram were cut out and reassembled as shown. (B) Restriction map of the BAC transgene. The sizes of key restriction fragments are shown below the diagram of the β-globin cluster. (N, NotI; S, SalI; K, KpnI; H; HindIII.) *Restriction sites derived from the pBeloBAC vector and not the β-globin cluster.