Bak regulation is independent of initial subcellular localization.

<p>(<b>A</b>) Schematic of Bak-mediated apoptosis initiated by Noxa-Mcl-1 signalling in MEFs. The four prosurvival proteins expressed in MEF (Mcl-1, Bcl-x_L, Bcl-w and Bcl-2) are depicted, together with their preferential binding of BH3-only proteins (Noxa, Bim and Bad) and of Bak and Bax <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031510#pone.0031510-Willis1" target="_blank">[20]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031510#pone.0031510-Chen1" target="_blank">[46]</a>. The Noxa-Mcl-1-Bak pathway to apoptosis is indicated (<i>bold</i>). (<b>B</b>) Expression of Bim_S^NOXA preferentially mediates apoptosis via either Bak or Bak/BaxCS. <i>bak^−/−bax^−/−</i>MEFs expressing the indicated Bak and Bax variants were retrovirally infected with Bim_S or with Bim_S containing the Bad or Noxa BH3 domains (Bim_S^BAD and Bim_S^NOXA). Percentage cell death at 36 h (normalized to the efficiency of infection) is expressed as the mean ± SEM of three independent experiments. Statistical significance for treatment when compared to Bak; **p<0.01.