Many scientists make the mistake of capitalizing western when publishing articles on the assay technique, western blot analysis. In fact many popular websites capitalize western routinely, consider Retraction Watch and ResearchGate amongst the perpetrators.

It all leads back to the development of the Southern blot; when Edwin M. Southern first demonstrated DNA fragments fractionated in agarose gels could be transferred to a solid support and detected as discrete bands, the technique was named after him. When the technique was applied RNA, it was named the ‘Northern ‘blot. And, when it was applied to the transfer of proteins that would be detected by antibodies, the name “western’ blot was applied.

According to Daniel Klionsky of the Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, capitalization of any blot except the Southern, this is incorrect.

Klionsky points out Southern is properly capitalized as a proper noun. Read about it here: https://dx.doi.org/10.1080%2F15548627.2016.1255382