The present study examines the influence exerted by affiliate directors in the diversification decisions of family-controlled, publicly traded firms. Using a relational view based on the development of social capital, we argue that affiliate directors play a different role in boards of family firms vis-à-vis nonfamily firms. Specifically, we develop a set of hypotheses proposing that affiliate directors stimulate family firms to pursue diversification strategies by sharing their knowledge and experience with family executives, and hence reducing the perceived risk that may be associated with growth strategies. Affiliates can play this advisory role without reducing the control of family owners, and this facilitates the firm's willingness to adopt growth-oriented strategies. Namely, affiliates who are business experts or support specialists would tend to encourage diversification. These effects are supported empirically.

Research on human capital as a source of competitive advantage has focused largely on firm employees. In this article, we argue that outside directors' general human capital can also be a source of competitive advantage. Firm performance is likely to benefit from directors' human capital-that is, their prior experience and education-because such human capital is likely to make them more effective at monitoring management and providing advice. Drawing on insights from research on individuals' cognitive limitations, we further argue that the extent to which the firm is able to benefit from this human capital can be severely limited by the demands for information processing that directors face from their other board positions. Consequently, we find that the benefit of directors' human capital is contingent upon the information processing load placed upon them from their other board appointments. We find support for our hypotheses using data on over 5,700 directors from 650 firms sampled from the Fortune 1000. This study extends the nascent literature on board human capital by showing that in addition to specific expertise in relevant areas, directors' general human capital can also help firms create competitive advantage. The theory developed in this article also contributes to the literature on strategic human capital by incorporating the concept of information processing demands, suggesting that not only do such demands leave limited cognitive capacity for directors to focus on the focal firm but also that they can severely diminish the beneficial effects of directors' general human capital.

Mutations in PINK1 and PARKIN cause early-onset Parkinson's disease (PD), thought to be due to mitochondrial toxicity. Here, we show that in Drosophila pink1 and parkin mutants, defective mitochondria also give rise to endoplasmic reticulum (ER) stress signalling, specifically to the activation of the protein kinase R-like endoplasmic reticulum kinase (PERK) branch of the unfolded protein response (UPR). We show that enhanced ER stress signalling in pink1 and parkin mutants is mediated by mitofusin bridges, which occur between defective mitochondria and the ER. Reducing mitofusin contacts with the ER is neuroprotective, through suppression of PERK signalling, while mitochondrial dysfunction remains unchanged. Further, both genetic inhibition of dPerk-dependent ER stress signalling and pharmacological inhibition using the PERK inhibitor GSK2606414 were neuroprotective in both pink1 and parkin mutants. We conclude that activation of ER stress by defective mitochondria is neurotoxic in pink1 and parkin flies and that the reduction of this signalling is neuroprotective, independently of defective mitochondria. A video abstract for this article is available online in the supplementary information

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