Probiomed 1 article published in JoVE Medicine Determination of the Relative Potency of an Anti-TNF Monoclonal Antibody (mAb) by Neutralizing TNF Using an In Vitro Bioanalytical Method Lilia Tierrablanca-Sánchez1, Víctor Pérez Medina Martínez1, Nancy D. Ramírez Ibañez1, Néstor O. Pérez Ramírez1, Francisco Luis Flores Ortiz1, Emilio Medina-Rivero2 1Research and Development, Probiomed, 2Bioprocess Research and Development Unit, Instituto Politecnico Nacional A protocol for the determination of the relative anti-apoptotic activity of an anti-TNFα mAb using a neutralization mechanism with WEHI 164 cells is presented here. This protocol is useful for comparing the neutralization strength of different molecules with the same biological functionality.