Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

[EX Q]: Context: During the war, the Russian army organized the Crimean campaigns of 1687 and 1689 both which ended in Russian defeats. Despite these setbacks, Russia launched the Azov campaigns in 1695 and 1696, and after raising the siege in 1695 successfully occupied Azov in 1696. 
 Question: who lost the Crimean Campaigns?
[EX A]: russia

[EX Q]: Context: Ceraunius Tholus is a volcano on Mars located in the Tharsis quadrangle at 24.25 north latitude and 262.75 east longitude, part of the Uranius group of volcanoes. 
 Question: On what moon or planet can Ceraunius Tholus be found?
[EX A]: mars

[EX Q]: Context: Since reports that precursor cells in the adult subventricular zone (SVZ) contribute to regenerative neuro- and gliogenesis in CA1, we wondered whether a similar route of migration might also exist under physiological conditions. Permanent labeling of SVZ precursor cells with a lentiviral vector for green fluorescent protein did not reveal any migration from the SVZ into CA1 in the intact murine brain. However, in a nestin-GFP reporter mouse we found proliferating cells within the corpus callosum/alveus region expressing nestin and glial fibrillary acidic protein similar to precursor cells in the neighboring neurogenic region of the adult dentate gyrus. Within 3 weeks of BrdU administration, BrdU-positive nestin-GFP-expressing protoplasmic astrocytes emerged in CA1. Similar to precursor cells isolated from the dentate gyrus and the SVZ, nestin-GFP-expressing cells from corpus callosum/alveus were self-renewing and multipotent in vitro, whereas cells isolated from CA1 were not. Nestin-GFP-expressing cells in CA1 differentiated into postmitotic astrocytes characterized by S100beta expression. No new neurons were found in CA1. The number of nestin-GFP-expressing astrocytes in CA1 was increased by environmental enrichment. We conclude that astrogenesis in CA1 is influenced by environmental conditions. However, SVZ precursor cells do not contribute to physiological cellular plasticity in CA1. 
 Question: Which intermediate filament (IF) protein can be used as a non-specific marker of the neuronal precursor cells of the subventricular zone?
[EX A]:
nestin