Fig. 7. Repression by the unliganded ecdysone receptor is lifted at different steps in neurogenesis for different sets of SOPs. For the chemosensory neurons of the margin we speculate that BR-Z2 activates SENS whereas BR-Z1 is required for the accumulation of SENS in the mature SOP. BR-Z1 is repressed by the unliganded EcR/USP complex. The control of br-Z2 expression has not been established. The early born SOPs accumulate SENS prior to the rise of 20E and are independent of BR function. EcR/USP repression inhibits the division of the SOP. The rise in 20E relieves repression and allows the SOP to divide. Grey represents low levels of SENS protein [adapted from Jafar-Nejad et al. (Jafar-Nejad et al., 2003)]; black shows the mature SOPs that have accumulated SENS. Open arrow marks the rise in 20E.