When a handshake won't do, some military men and women will reach out and just hug the person who came by to welcome them home.

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However, before the alarm can be sounded in this way, proteins on the surface of the antigen-presenting cell and the T cell must bind together in what is called a cellular handshake.

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Alex felt helpless, livid at being judged by a handshake and his skin color, but he knew it didn't have anything to do with him.

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