San Francisco 49ers quarterback Colin Kaepernick was booed by the Buffalo Bills' fan base prior to Sunday's game, with a faction breaking into a "USA" chant prior to his protest during the national anthem.
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Kaepernick is kneeling during the national anthem this season as a form of protest against police brutality and racial inequality, and the movement has gained national attention over the past two months.
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The quarterback is making his first start of the season, replacing Blaine Gabbert.