FIG. 5.

Proliferation of EREB2.5 cells constitutively expressing Notch1IC after estrogen starvation. (A) Notch1IC protein efficiently transactivates luciferase gene under the control of a promoter containing multimerized CBF1-binding sites. Either Notch1IC- or EBNA2-expressing effector plasmids were transiently cotransfected with the luciferase reporter plasmid pJT123 into DG75 cells. Luciferase activity was quantified for different amounts of the effector plasmids. T-bars indicate standard errors. (B) Western blot analyses of Notch1IC or EBNA2 proteins in cells transiently transfected with the respective effector plasmids (as in panel A). (C) Ten thousand cells/well of the indicated cells were plated into 96-well plates in growth medium without estrogen. Cell proliferation was monitored by MTT assays as described in Materials and Methods each day over the course of 6 days. (D) Same as for panel C, except that cells were grown in media containing estrogen.