Specificity of 618F for human MUC16. (A) Purity of human MUC16 isolated from spent media of OVCAR-3 cells as determined by Coomassie Blue (1) and silver staining (2) of SDS-PAGE gel. Western blot analysis of the purified human MUC16 was conducted using the 618F (3) and the VK-8 (4) antibodies. (B) MUC16 expression on OVCAR-3, CAOV-3, and SKOV-3 was determined by flow cytometry using 653F, 618F, or VK-8 as the primary antibodies. Mean fluorescence intensity of the corresponding isotype controls was subtracted in each case. Data shown is mean of two independent experiments. Note that the binding of 618F, 653F and VK-8 to these three cell lines is comparable.