Differences in Medium-Induced Conformational Plasticity Presumably Underlie Different Cytotoxic Activity of Ricin and Viscumin oleh Pavel Volynsky, Diana Maltseva, Valentin Tabakmakher, Eduard V. Bocharov, Maria Raygorodskaya, Galina Zakharova, Elena Britikova, Alexander Tonevitsky, Roman Efremov