4.2. Immunohistochemistry Staining and Scoring

Briefly, the arrays were rehydrated and autoclaved at 121 °C for 10 min in a citrate buffer (Fisher Scientific, Rockford, IL, USA) to retrieve the antigens. They were incubated with 3% H₂O₂ for 10 min and with 10% bovine serum for 1 h to block non-specific signals. Sections were incubated overnight at 4 °C with antibodies against PLZF (1:200; abCam, Cambridge, MA, USA), pY-STAT3 (1:50; cell signaling, Danvers, MA, USA), and SHP-1 (1:200; abCam). Immune complexes were visualized using the Vectastatin ABC kit (Vector Laboratories, Burlingame, CA, USA) and the DAB detection kit (Dako, Carpinteria, CA, USA). Finally, all sections were counterstained with hematoxylin. Positive staining cells were counted on 5 randomly chosen visual fields at 400× magnification by means of ImageJ (National Institutes of Health, Bethesda, MD, USA).