FIG. 5.

Silencing of EGFP expression in single-copy clone HS2(7.5)γEGFP-4. The clone was grown for 26 or 36 days with or without hygromycin (hygro) and then treated with 5 nM TPA (shaded) or vehicle (unshaded) for 20 h before each analysis. The percentage of EGFP-positive cells in the viable cell population was measured by flow cytometric analysis. EGFP was quantitated in cell lysates by fluorometry and normalized by protein concentration and the copy number of the integrated reporter construct.