Figure 5

Cell cycle arrest in response to ectopic Dpp. (A) Inducible expression of GFP in clones did not affect cell proliferation in eye discs (BrdU incorporation in magenta); (B) Inducible expression of Dpp in clones almost completely eliminated BrdU incorporation (magenta) throughout the eye disc, antennal disc, and peripodial membrane; (C) Inducible expression of GFP in clones did not affect cell proliferation in eye discs (phospho-H3 labeling in magenta); (D) Inducible expression of Dpp in clones greatly reduced phospho-H3 labeling of mitotic figures; (E) Inducible expression of GFP in clones did not affect CycB expression in eye discs (magenta); (F) Inducible expression of Dpp in clones led to complete loss of CycB expression posterior to the morphogenetic furrow. Anterior to the position where cells normally arrest in G1, where wild type discs contain cells at varied cell cycle stages, ectopic Dpp led to accumulation of CycB in all the arrested cells. CycB in magenta; (G) Even a small proportion of cells expressing Dpp were sufficient for intense Mad phosphorylation (magenta) throughout much of the eye antennal disc. Posterior to the furrow, however, highest levels of pMad were only seen in the cells expressing Dpp themselves; (H) High pMad levels throughout the peripodial membrane of the disc also shown in panel G; (I) pMad labeling in a wild type eye disc processed and recorded in parallel to the disc in panels G and H.