Fig. 4. Multiple regulatory elements are required for EGL-43 expression in the AC, DU and VU lineages. (A) Results of the site-directed mutagenesis study and fos-1 RNAi are summarized. White areas represent the absence of egl-43::YFP expression. Green areas represent the presence of YFP expression at specific developmental stages. The areas marked in light green represent decreased egl-43::YFP expression. (B) Model summarizing egl-43::YFP expression patterns in the somatic gonad. The ACEL-like element containing two E-boxes is the major enhancer expressing EGL-43 in the pre-AC/pre-VU cells and in the AC, but not in the VU cells. LAG-1 binding sites are also required for EGL-43 expression in the pre-VU cells when AC/VU cell fates become specified. Unidentified enhancers increase EGL-43 expression in the VU cells and their descendants from late L2, and in the AC from mid-L3.