Fig. 7. Model for Arabidopsis trichome/non-trichome cell fate specification. Regulators of trichome fate are green shades, activators (GL2/TTG2) are yellow and inhibitors (CPC/ETC1) are orange. Black arrows indicate transcriptional activation. In trichome cells, the inhibitors are directly activated by the activating complex and move (broken lines) into neighboring cells, where they and endogenous inhibitors block the activity of the activating complex thereby decreasing the expression of GL2/TTG2 to below a required initiating threshold level (broken arrows). Thus, the trichome cell fate is not triggered.