How can I compare the biological activities of products from different vendors?

Biological activities of products from different vendors can only be compared if the cellular assays are calibrated with a defined international standard (from the NIBSC), or if the samples are
measured in parallel using the same assay, the same batch of cells, and the same set of conditions. Because even minor variations in assay conditions can result in different activity, we use the NIBSC standard whenever possible. For product-specific comparison data, please have a look at the product pages online. In addition, it is recommended to determine the optimal concentration for your specific application by a dose-response experiment, because the standardized assay for determination of the biological activity cannot comprise all possible aspects of different applications.

The biological activity of Human EGF was determined by a proliferation assay using 3T3 cells. Human EGF, premium grade, (dark color) was compared to another commercially available product (light color).