Mass spectrometry reveals stable modules in holo and apo RNA polymerases I and III. Bằng Lane, L, Fernández-Tornero, C, Zhou, M, Morgner, N, Ptchelkine, D, Steuerwald, U, Politis, A, Lindner, D, Gvozdenovic, J, Gavin, A, Müller, C, Robinson, C