In vitro T268M repair. (a) Allele-specific RT-PCR amplification of a 358-bp trans-spliced product from cells treated with ribozyme. Inactive ribozyme–treated T268M-stable cells, nontransfected T268M-stable cells, and a mix of ribozyme-treated HEK-293 cells and T268M-stable cells failed to yield a product. (b) Representative sequence trace of repaired cClC-1 sequence. The targeted uridine (T/U712) and the trans-splice junction are labeled. Underlined bases represent the sequence tag.