"We wished to distinguish whether CEH-17 and CEH-14 act in a single pathway that activates target gene expression in ALA, or whether they function in parallel. If these factors act in parallel, we would expect to see enhancement of the
ceh-14 null mutant phenotype by the
ceh-17 null mutation. As the expression of our
let-23 reporter gene is nearly abolished in the
ceh-14(
ch3) single mutant (Table 2), we could not use it as a readout of target gene expression in a double-mutant analysis. We therefore examined the expression of
plc-3:YFP, which is expressed in a fraction of each of the single mutants. We found expression of the
plc-3 reporter gene to be completely abolished in the
ceh-14(
ch3);
ceh-17(
np1) animals (0/78 show expression, P<0.0001 versus
ceh-14(
ch3) alone, t-test with Welch correction)."