Figure 5

Expression of Notch pathway component proteins in urothelial cells. Western Blot analysis of Notch ligands and receptors in urothelial cancer cell lines compared to a primary normal urothelial cell culture (UP). Top to bottom: Analysis with a JAG1 antibody resulted in two signals at approximately [1] = 170 kD and [2] = 130 kD, likely corresponding to JAG1 full-length protein and its processed extracellular domain. Signal [2], in particular, was strongly decreased in invasive UC cell lines compared to normal urothelial and papillary UC cells. DLL1 protein was detectable at the expected size of 75 kD [3]. The signal was decreased in invasive UC cell lines compared to papillary UC and normal urothelial cells. Analysis with NOTCH1 antibody resulted in an approximately 120 kD band [4] indicating a C-terminal NOTCH1 fragment which was strongly diminished in urothelial cancer cell lines. Band [5] at ~300 kD likely corresponds to full-length NOTCH2 protein and band [6] at ~120 kD to the processed C-terminal NOTCH2 fragment. No general decrease in expression is discernible in the UC cell lines. α-Tubulin (Sigma) was used as a quality and loading control.