Fig. 6. The mutant CeTwist E29K protein cannot cooperate in vivo with CeE/DA to activate a reporter construct. Animals that had an integrated egl-15::gfp reporter construct plus extragenic heat shock expression construct(s) indicated were subjected to heat shock and after a period of recovery were scored for the amount of GFP expression observed. Two lines each of the expression constructs were scored. Embryos expressing CeTwist and CeE/DA from the heat shock promoter are labeled Wild type CeTwist. Embryos expressing CeTwist E29K and CeE/DA from heat shock promoters are labeled CeTwist E29K. Cells where either CeTwist or CeTwist E29K plus CeE/DA were overexpressed from the heat shock promoter were observed by immunostaining embryos with either the CeTwist or CeE/DA antibody (B,F or D,H, respectively). Representative embryos are shown. (A,C) Expression of egl-15::gfp was observed only in cells where CeTwist and CeE/DA were ectopically expressed. (E,G) Only background levels of fluorescence can be seen when mutant CeTwist E29K and CeE/DA are overexpressed in egl-15::gfp-containing embryos.