Fig. 1. Effects of v-Src on the expression of TGF-ß RII in myeloid cell lines. A, cross-linking of 125I-labeled TGF-ß1 to receptors on 32D-123 and 32D-src murine myeloid cell lines. Aliquots of 5 x 106 cells were suspended in binding buffer with 125I-labeled TGF-ß1 in the presence or absence of an excess of unlabeled TGF-ß1, followed by incubation with 100 µg/ml of disuccinimidyl suberate. Affinity-labeled sample were resuspended in lysis buffer and analyzed on SDS-PAGE. A 40-fold molar excess of unlabeled TGF-ß1 was added into the reaction. Numbers at the left of 32D-123 and at the right of 32D-src indicate the positions of molecular weight size markers. B, Northern analysis of the expression of TGF-ß RII gene. Poly(A)+ RNAs of 32D murine myeloid cell lines were isolated for Northern analysis (Lane 1, 32D-123; Lane 2, 32D-src cell line). A 1.5-kb fragment of RII gene was used to detect the mouse RII transcript. The actin gene was used as an internal control. A 1.5-kb fragment was used as a probe to show the expression of the v-src gene. C, Western blot analysis of v-Src protein (Mr 60,000) in 32D myeloid cell lines (Lane 1, 32D-123 cell line; Lane 2, 32D-src cell line). Protein extracts were separated by SDS-PAGE, and Western blot analysis was performed with mouse monoclonal anti-v-Src antibody.