Analysis of BMP4 expression during the recovery from acute anemia. (A) RT-PCR analysis of BMP4 expression in C57BL/6-+/+ control (left) and C57BL/6-f/f (right) mice. Arrows indicate the positions of the BMP4-specific band and the hypoxanthine guanine phosphoribosyl transferase 1 (HPRT) control band and the number of PCR cycles is indicated at the right. (B) Spleen sections from C57BL/6-+/+ (top row) and C57BL/6-f/f (bottom row) mice stained with anti-BMP4 antibodies at the indicated times following PHZ-induced acute anemia. BMP4 staining was visualized using an Olympus FV300 confocal laser scanning microscope equipped with a UPLANFL 100×/0.3 objective lens (Olympus, Melville, NY). Images were acquired using Fluoview version 4.3 software (Olympus). (C) RT-PCR analysis of BMP4 expression in MSS31 spleen stromal cells grown at normoxic (20%) and hypoxic (6%) conditions (top). The position of the putative hypoxia-inducible element in the BMP4 gene is indicated and an alignment of this sequence from mouse, human, and rat is presented (bottom).