Figure 8. Cultured cells show the same responses observed in embryos with gain or loss of Notch activity.

A. TPA treatment of cl8 cells (that express Notch endogenously) increases the level of P-Cactus and cytoplasmic Dorsal. The same samples were used for the three blots. B. Cell fractionation of cl8 cells treated with TPA shows the expected cytoplasmic localization for P-Cactus and nuclear localization for P-Dorsal and MAD proteins. The same samples were used for all four blots. Lamin is a nucleus specific marker. C. TPA activation of PKC in S2-Notch or cl8 cells increases the level of MAD protein. In all the experiments the same number of cells was used for each sample and the same amount of the sample was loaded in all lanes. TPA treatment was for 30 minutes. Experiment under A was repeated four times (with different time samplings), experiments under B was repeated three times, and experiments under C twice.