Soon after criticizing the Miami Dolphins for protesting during the national anthem on Sunday, Kate Upton was attacked on Twitter with sexist messages.Upton chose to pay tribute to those who lost their lives on 9/11 on Instagram with a photo of her boyfriend, baseball player Justin Verlander, standing with his hand over his heart during the national anthem."I choose to stand. Remembering all those who lost their lives 15 years ago on 9/11," she wrote. "Also, the countless who've given their lives defending our freedom here at home. #NeverForget #PatriotDay."But, after the Dolphins chose to take a knee as the national anthem played during their afternoon game, Upton took to Twitter to comment on what she felt was a sign of disrespect."This is unacceptable. You should be proud to be an American. Especially on 9/11 when we should support each other," she wrote. "Protest & speak ur mind whenever u want but during the 120 secs you should support the people who protect our freedom."She added, "In my opinion, the national anthem is a symbolic song about our country. It represents honoring."