The rol-6 co-injection marker causes an expressional artifact in CP09.

GFP expression in the male tail of transgenic worms injected with an empty GFP vector (pPD95.75) along with rol-6(su1006) plasmid (pRF4) (A) or ttx-3p::GFP plasmid (B). Exclusive CP09 expression was observed in seven out of 12 independent transgenic lines injected with GFP vector + pRF4 (7/12), whereas no CP09 expression was observed in 10 independent lines with GFP vector + ttx-3p::GFP (0/10). Asterisks indicate autofluorescence in the spicule. Scale bar, 20 μm.