Fig. 7. Model of transcriptional regulation of early SPCGs. Fkh and CrebA are directly regulated by the Scr/Exd/Hth complex. Late expression of CrebA requires Fkh and Fkh is autoregulated. The expression of most of the SPCGs is greatly reduced in CrebA mutants at all embryonic stages, whereas only late (beyond stage 13) expression of all tested SPCGs is affected by the loss of fkh function. As late expression of the SPCGs was lower in late fkh mutants than in CrebA mutants, we propose the existence of another early transcription factor gene in SPCG regulation. As with CrebA, late but not early expression of this putative transcription factor would require Fkh.