Smad4^Δ/Δ mice developed anemia after induced Smad4 deletion. Hemoglobin level, hematocrit, reticulocyte count, leukocyte count, mean corpuscular volume (MCV), and platelet count in Smad4^Δ/Δ (n = 3), Smad4^fl/fl (n = 4), and Smad4^Δ/+ (n = 8) mice were plotted against weeks after induction. The P values were calculated by Student t test. The error bars indicate standard deviation.