Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:‚Ä¶in bulk cytosolic Ca21 concentration, caused a significantly smaller activation of MAPK in comparison with that resulting from glutamate receptor stimulation, supports the hypothesis that MAPK requires high localized Ca 21 rises for its activation in neurons (Finkbeiner and Greenberg, 1996, 1997).
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