Soluble TGF-β1 specifically decreased the level of pRb phosphorylation.

CD34⁺ progenitors were incubated in the presence or absence of soluble TGF-β1 or neutralizing antibody to TGF-β1 (a-TGFB) for 48 hours. Total lysates were run on 7.5% SDS-PAGE gel and transferred onto Immunobilon membrane. (A) Immunoblotting with an antibody that recognizes underphosphorylated, hypophosphorylated, and hyperphosphorylated forms of pRb. (B) Immunoblotting with an antibody specific to Ser811 pRb. Membranes were also stained in amido black staining to ensure equal protein loading in all lanes.