Chemiluminescent Western Blot
Typical two step blots have the protein of interest with the primary antibody that is able to probe it, anti-mouse in this case. Then a secondary antibody that is able to hybridize to the anti-mouse body, goat anti-mouse.
Substrate is luminol chemiluminescence. Horseradish peroxidase and a peroxide buffer is in one bottle, the luminol is in the other. Mixing the two will lead to the luminol oxidizing to emit a light at 425 nm that can be detected with UV.
Luminol is the same chemical as what crime scene investigators use to detect blood. Which makes sense, what are antibodies if not just blood.