ADAMTS4 and Stroke: Because TNF-α was shown to promote ADAMTS-1 and -4 mRNA levels as well as ADAMTS-4 and -5 protein levels in human astrocyte cultures, it was hypothesized that the increase of TNF-α expression in the acute phase of stroke may be responsible for the upregulation of ADAMTS-1 and -4 by astrocytes [23].