Figure 4.

Pancreatic cancer cell lines express variable levels of CXCR4A and CXCR4B transcripts. (A) Schematics of the CXCR4 gene locus, including exon 1 with the start site for CXCR4B (canonical transcript), intron 1, alternative start site for CXCR4A (alternative transcript CXCR4-Lo), and exon 2, including the stop codon and the 3′ untranslated region. (B) Schematics for the CXCR4B transcript encoding the canonical CXCR4 protein, and the alternatively spliced CXCR4A transcript of the CXCR4-Lo protein. The resulting protein products are identical except for short peptides at the N-terminal ends. (C) Reverse transcription quantitative polymerase chain reaction analysis of CXCR4A and CXCR4B transcripts in a panel of pancreatic cancer cell lines. Bars represent three independent experiments. Relative expression units are set so that a unit of 1 equals the average total levels of transcript in MIA PaCa-2 cells. CXCR4, C-X-C chemokine receptor 4; CXCR4A, CXCR4 transcript variant A; CXCR4B, CXCR4 transcript variant B.