endogenous and recombinant EPO. The possible presence of proteases can be assessed using the Protease Fluorescent Detection Kit (Sigma-Aldrich), but there are some limitations: low sensitivity in biological matrices [...] Elution was performed with 5 µL of Glycine 0.1M pH2.8 for 10 minutes at RT. Then, 1.25 µL of Fluorescent Master Mix 5X solution was added, and samples were heated at 95°C for 3 minutes before Simple Western