Representative histology of mice transplanted with Skp2^+/+ and Skp2^−/− marrow transduced with p210^BCR-ABL or empty vector. (A) Spleen, liver, and lung [hematoxylin and eosin (H&E) stain, original magnifications are ×5, ×20, and ×20, respectively]. Higher magnification ×40 is also shown in the lower right corners. (B) Peripheral blood smear (Wright-Giemsa stain, original magnification ×63), and bone marrow (H&E stain and reticulin fiber stain, original magnification ×40). (C) p27 Immunohistochemistry of spleen of mice that received Skp2^+/+ and Skp2^−/− marrow transduced with empty vector (i, ii) or p210^BCR-ABL (iii, iv). p27 Staining was performed using polyclonal anti-p27 primary antibody (C19; Santa Cruz Biotechnology) and biotinylated anti–rabbit IgG (H&L) secondary antibody (Vector Laboratories, Burlingame, CA) using Vectastain Elite Universal ABC Kit (Vector Laboratories) and DAB Chromogen (Dako, Carpinteria CA). Nuclear and cytoplasmic p27 are indicated by black and red arrows, respectively. For negative controls, staining with IgG antibody (v) and with anti-p27 antibody including p27-specific blocking peptide (Santa Cruz Biotechnology) showing practically complete block of p27 staining in cells with some residual background staining (vi). Original magnifications, ×100. Images were viewed with a Leica DM LB2 microscope (Leica, Wetzlar, Germany) equipped with Leica N Plan 5×/0.12 (for 5× magnification), HC PL Fluotar 20×/0.50 (20×), HCX PL Fluotar 40×/0.75 (40×), C Plan 63×/0.75 (63×), and N Plan 100×/1.25 oil (100×) objective. Images were captured with a Leica DC300 camera running IM50 Image Manager software (v5 release 222; Heerbrugg, Switzerland) and processed with Adobe Photoshop CS2 9.0.2 (Adobe Systems, San Jose, CA).