New research on the properties of the clot-busting stroke drug tPA (tissue-type plasminogen activator) suggests that tPA can act as a neuroprotectant and may form the keystone of an adaptive response to a reduction in blood flow. Scientists have shown that certain parts of the brains of mice lacking the gene for tPA are more vulnerable to stroke. In addition, tPA can protect neurons in the same part of the brain from the stress of hypoxia (low oxygen).