RAP-536 inhibits Smad2/3 activation in Hbb^th1/th1 mice. (Upper) Representative phospho-Smad2/3 immunostaining (brown) in hematoxylin-counterstained spleen sections from a wild-type mouse (Wt), a vehicle-treated Hbb^th1/th1 mouse (th1/th1), and an Hbb^th1/th1 mouse treated for 12 hours with a single dose of RAP-536 (30 mg/kg, intraperitoneally, n = 3-4 mice per group). (Insets) Higher magnification. (Lower) Representative Ter119 immunostaining (brown) denoting red pulp in adjacent hematoxylin-counterstained spleen sections. *White pulp. Images were obtained with a 20× objective or 100× oil immersion objective. Bar = 100 or 15 µm (insets).