The rol-6 fragment of pRF4 is responsible for CP09 expression.

(A) Schematic of cloning procedure to identify a region of pRF4 plasmid responsible for CP09 expression. Either rol-6 or vector fragment was subcloned into the empty GFP vector pPD95.75 and the resulting plasmids were injected to generate transgenic worms. (B) CP09 expression was observed in all 12 independent transgenic lines injected with rol-6 fragment::GFP (12/12), whereas no CP09 expression was observed in nine independent lines with vector fragment::GFP (0/9). (C) Proposed model of homologous recombination between pRF4 plasmid and GFP constructs.