CD81 and urinary bladder cancer: This difference could also be well appreciated when 5637 cells lysates were analyzed by western blot: the quantitative ratio between CD9-RFP CS or CD81-RFP CS and their respective CD9 or CD81 basal forms resulted, in fact, to be visibly lower compared to CD9-RFP NACS or CD81 RFP NACS and CD9 or CD81 basal forms, indicating a high protease specificity against the inserted active cleavage site in the bladder cancer cells expressing cathepsin B (Figure 2(B) and 2(C)).