RNase protection analysis with the 791-bp Hae III probe (residues 2166 to 2957). RNA from 11 of 24 samples protects a full-length fragment, indicating that 791 bp of sequence identify with KB C-1 from which the probe was derived. RNA from 12 of 13 remaining samples (bold) protects both full-length probe and two additional fragments of 511 bp and 280 bp as a result of a mismatch at position 2677 (includes HCT-15, LS180, LS180 Ad50, DLD-1, and DLD-1 Vb300 not well visualized here). Vb, vinblastine; Ad, adriamycin.