Prior to vulval induction, the reIs3 Pchw-1::gfp-containing transgene failed to express GFP in the six VPCs, but is visible in surrounding cells. Upon EGF induction GFP was expressed in non-vulval (3) VPC lineages and surrounding cells, but was excluded from VPC lineages that had been induced to form vulva (P5-7.p and subsequent 2-1-2 lineages). The exclusion extended throughout larval development, and all expression faded after the L4 stage.