Identification of HS2 core, HS2 core inverted, and HS2 full deletion clones. (A) Map shows the Southern strategies to screen the modified ES clones. N indicates cutting sites for NheI; the short line under the maps, the probe; and ▨, the CMV-HyTK gene after homologous recombination. The expected band sizes are noted. (B) ΔHS2 full deletion Southern blot. Lanes 1 and 5, ΔHS2 full/S; lane 2, D/S; and lanes 3 and 4, HS2(HR)/S. (C) ΔHS2 core deletion Southern blot. Lanes 1 and 3, ΔHS2c/S; lane 2, ΔHS2c(inv)/S; lane 4, HS2(HR)/S; and lane 5, D/S.