Figure 1: Constitutive phosphorylation of DDR1 in Calu-3 cells lysed in the presence of phosphatase inhibitors* (phospho lysate) is detected by PathScan ® Phospho-DDR1 (panTyr) Sandwich ELISA Kit #7863 (upper, right). In contrast, a low level of phospho-DDR1 protein is detected in Calu-3 cells lysed in the absence of phosphatase inhibitors* (nonphospho lysate). Similar levels of total DDR1 protein from both nonphospho and phospho lysates are detected by PathScan ® Total DDR1 Sandwich ELISA Kit #7845 (upper, left). Absorbance at 450 nm is shown in the top figure while corresponding western blots using a Phospho-DDR1 (Tyr792/796/797) rabbit antibody (right) or a total DDR1 rabbit antibody (left) are shown in the bottom figure. *Phosphatase inhibitors include sodium pyrophosphate, β-glycerophosphate and Na 3 VO 4 .