Beta-1 integrin (CD29) expression on HPCs and erythrocytes. CD29 expression of freshly isolated HPCs (middle) and erythrocytes (right) was determined by FACS analysis. 20 000 cells were analyzed and the number of CD29⁺ cells is given as the percentage of the total number of cells. All stainings were referred to isotype-matched control antibodies (left). Cells expressing CD29 are given right of the dotted line (upper fluorescence limit of isotype control).