Fig. 10.

‘Bow-tie’ models of cellular networks. There are many examples of cellular networks in which a large variety of possible initial events leads to complex sequelae, but these are mediated via a comparatively small number of ‘intermediate’ reactions. While in the present case it is suggested that these in part involve complex positive feedbacks, the general ‘bow-tie’ idea does allow one to recognise that despite the many different possible inputs, a broadly unitary kind of mechanism of action—here involving iron dysregulation—can reasonably be invoked to explain the multiple causes that can lead to cell death and destruction