Cbl deletion mutant. (A) Exons 7-9 of the wild-type and mutant Cbl gene. Deletion of the exon 8 splice acceptor causes exon 8 to be spliced of the transcript. (B) CBL protein structure showing known functional domains. Y indicates tyrosine residue that is phosphorylated to activate CBL function. (C) Nucleotide sequence at breakpoint, demonstrating 6 base pair microhomology. (D) Expression of the mutant allele. Lane 1, 1 kb ladder, lane 2, cbl mutant, lane 3, wild-type control, lane 4, no template. Note the lower PCR product in lane 2 corresponding to the mutant allele.