YB-1 regulates G3BP1 expression in vivo. (A) MNNG shControl or shYB-1 kd cells were implanted under the renal capsules of three independent pairs of NOD/SCID mice, and primary site tumors were collected 4–5 wk after implantation. Viable regions of tumors were cryosectioned and subjected to IF with anti–YB-1 (green) or anti-G3BP1 (red) antibodies, and counterstained with DRAQ5 to detect nuclei. Insets show fivefold higher magnification of indicated areas. 10 high-power fields (HPF) of representative tumor sections from each implantation site tumor (n = 3 per group) were used for quantification of SGs as in Fig. 1 B, as shown below with a bar graph. Mean values ± SD (error bars) are shown for three independent tumors. **, P < 0.01. Bars: (main panels) 10 µm; (enlarged insets) 1 µm. (B) Lysates extracted from tumor tissues from A were subjected to immunoblot analysis using the indicated antibodies.