FGFR3 and urothelial carcinoma: As a model system to evaluate the ability of the device to capture and enumerate tumor cells from fluid samples, we used the 639V urothelial carcinoma cell line, which has a point mutation (p.R248C) in the gene encoding fibroblast growth factor receptor 3 (FGFR3) with loss of the corresponding wild type allele (S1 Fig).