It has been said that gene expression researchers measure messenger RNA (mRNA) because they can and not because they want to. Somewhat controversial perhaps, but the thought behind this is that measuring specific proteins and particularly functionally-active protein is all-important. However, the reality is that measuring functional protein activity requires a bespoke assay while measuring specific proteins invariably requires the use of antibodies. For new protein variants, antibodies are often unavailable, and even if they are, gene expression researchers have long-realized that antibodies frequently underperform in the lab. Embarking on the process of generating an antibody or a functional assay for a new protein variant is therefore not always straightforward.