Double staining for α-naphthyl butyrate esterase and naphthol AS-D chloracetate esterase of UG3 cells cultured with IL-3 (5 ng/mL; A), GM-CSF (1 ng/mL; B), M-CSF (100 ng/mL; C), and G-CSF (10 ng/mL; D) for 2 weeks. Original magnification, 200-fold. Histochemical analyses were performed using samples taken from four independent cell cultures.