Induction of HS proteoglycan expression during early erythroid differentiation in the murine multipotent cell line FDCP-Mix A4. Erythroid differentiation of the murine multipotent hematopoietic cell line FDCP-Mix A4 was induced by culturing the cells in FCS, Epo, and low IL-3. As a control, FDCP-Mix A4 cells were induced to differentiate along the granulocytic lineage by culturing the cells in FCS, GM-CSF, G-CSF, and low IL-3. Cells were metabolically radiolabeled by [³⁵S]-sulfate for 24 hours. In parallel, cultures were set up for mRNA isolation. Proteoglycans from the supernantant of FDCP-Mix-A4 cells obtained at different time points after induction of erythroid differentiation were digested by chondroitinase AC/ABC, submitted to Sepharose Q anion exchange chromatography, and subsequently analyzed on a TSK 4000 column before (——) and after heparinase/heparitinase treatment (- - -). (A) The corresponding Northern blot analysis of β-globin mRNA expression (β-actin was used as control). (B) HS proteoglycan expression (analyzed as shown in part [D] as percent HS proteoglycan) in FDCP-Mix-A4 cells at different time points after induction of erythroid differentiation. (C) HS proteoglycan expression in FDCP-Mix-A4 cells at different time points after induction of granulocytic differentiation. (D) The respective chromatogram is given for day 2; the inset shows the corresponding Western blot of HS proteoglycan core protein using the MoAb 3G10 (see legend to Fig 8), and the 59-kD core protein is indicated by an arrowhead.