These include liquid chromatography mass spectrometry along with sodium dodecyl sulfate polyacrylamide gel electrophoresis, or liquid chromatography mass spectrometry run in multiple dimensions.
As the dye stained the polyacrylamide gel as well as the protein, to visualise the protein bands they needed to destain the gel which they did electrophoretically.
A sample (often cellular lysate) is separated on a polyacrylamide gel, transferred to a membrane and then probed with an antibody to the protein of interest.