Fig. 6. DDR1 expression by various HB2 cell populations. (A) DDR1 protein level detected in lysates of the following: non-transfected parental HB2 cells (lane 1), Wnt-5a-overexpressing cells (lane 2), Wnt-5a antisense cells (lane 3), and control cells (lane 4). (B) The tyrosine phosphorylation status of DDR1 receptors in various cell populations grown on collagen. Sample loading was done in the same order as in A. (C) DDR1 expression in MCF-7 control (lane 1), Wnt-5a-expressing MCF-7 (lane 2), and untransfected parental MCF-7 (lane 3) cells. (D) The tyrosine phosphorylation status of DDR1 receptors in various MCF-7 cell populations; sample loading was done in the same order as in 6C. (E) Tyrosine phosphorylation status of DDR1 receptors in cells grown on uncoated tissue culture plates; sample loading was done in the same order as in A. The molecular weight of DDR1 was estimated to 125 kDa by comparing with a molecular standard weight. The anti-DDR antibody reacts with isoform b/c (upper band) and with isoform a (lower band) of the DDR1 protein, but only isoform b/c is tyrosine phosphorylated.