Fig. 8. Proposed model for the involvement of GL3/EGL3 in a novel intercellular regulatory circuit. A WER/GL3/EGL3/TTG complex forms in cells in the N position and promotes expression of GL2 and CPC. Accumulation of GL2 in the N-position leads to the specification of the non-hair cell fate, while CPC/(TRY) moves laterally to the neighboring cell in the H position to form the inactive complex CPC/GL3/EGL3/TTG, which prevents expression of GL2 in the future hair cell. The presence of CPC/(TRY) in the H position also leads to activation of GL3 and EGL3 expression. In a lateral feedback loop, GL3/(EGL3) protein moves to the N cell to participate in the WER/GL3/EGL3/TTG complex, which activates GL2 and CPC and inhibits expression of GL3 and EGL3. See text for further discussion. Unbroken lines indicate gene transcription regulation; broken lines indicate protein movement; dotted lines indicate little/no transcription regulation. Proteins shown in white are at a low concentration.