Identification of the ΔCD20 splice isoform mRNA. Agarose gel electrophoresis of full-length (fl) PCR of the CD20 coding sequence from the Daudi and Raji cell line cDNA. Sequencing electrophoregrams of both full-length wt and truncated (ΔCD20) CD20 forms, showing juxtaposed part of the end of exon 3 (Ex) and exon 7. Localization of splicing sites (DS indicates donor site; and AS, acceptor site) on the RNA sequence (Ex1 to Ex8; UTR indicates untranslated regions). Correspondence of CD20 protein segments is shown (TM indicates transmembrane domains), and RTX epitope localization is indicated on wtCD20 as a hatched box. A schematic figure of the intracellular putative ΔCD20 is given for comparison to the wt protein. MW indicates the 100-bp molecular marker. ATG and TAA indicate start and stop codons, respectively.