PromoCell’s Cell Proliferation Assay Kit II (BrdU) detects incorporated BrdU using a mouse anti-BrdU antibody. An anti-mouse HRP-linked secondary antibody is used to detect the anti-BrdU antibody bound to BrdU, which is followed by addition of TMB (a HRP substrate). The extent of color development is proportional to the quantity of BrdU incorporated into the cells and can be used directly as an indicator of cell proliferation. Compared to other cell proliferation assays, this kit detects only the proliferating cells and not the seeded cells. This highly sensitive, non-radioactive kit detects as less as 50-100 proliferating cells.