Characterization of conditional Dicer knockout (CDKO) mouse embryonic fibroblasts (MEFs). (A) Wild-type (wt) and CDKO MEFs are shown, untreated (left panels) or 4 d after ortho hydroxy tamoxifen (OHT) treatment (right panels). Cells were stained for LacZ, and the percentage of LacZ-positive cells is shown (upper right). (B) Proliferation of wild-type and CDKO MEFs, untreated or following addition of OHT. Error bars represent standard deviation of three independent counts. (C) Western analysis of MEFcdko cells, untreated (lane 4) or after OHT addition (lane 5), showing a three- to fourfold reduction in Dicer protein levels following OHT addition. GAPDH is a loading control. Westerns using different concentrations of recombinant Dicer protein are shown as a positive control (lanes 1,2). (D) Microarray hybridization intensity change and expression level change measured by Northern analysis (log scale, both axes) for eight miRNAs (miR-21, miR-22, miR-23b, miR-34a, miR-92, miR-191, miR-199a*, and miR-200b).
