FIG. 6.

Prestalk gene induction and repression in ^act15cAR cell lines. RI9, ^act15cAR1, ^act15cAR2, and ^act15cAR3 cells were preincubated for 16 h in monolayers in the presence of 5 mM cAMP, washed, and incubated for 8 h without additives, with 100 nM DIF, and with 100 nM DIF plus 1 μM Sp-cAMPS. RNA was isolated and probed with ³²P-labeled ecmB mRNA. Sixteen-hour and 5-day exposures of the same Northern blot are shown. The experiment was repeated once with similar results.