Establishment of HeLa/rtTAA/TRE-N1-IC cell line. Establishment of HeLa/rtTAA/TRE-N1-IC cell line. A. An inducible HeLa cell line capable of doxycycline-controlled expression of human Notch1-IC was established as described in Materials and Methods. B. HeLa/rtTAA/TRE-N1-IC cells (5 × 105) were treated with concentrations of doxycycline (Dox; 0.01, 0.02, 0.1, 0.5, or 1 μg/mL). The induction of Notch1-IC and its downstream target gene HES1 expression were examined by immunoblot analysis. Jae Ho Lee et al. Mol Cancer Res 2009;7:1663-1671 ©2009 by American Association for Cancer Research