【单选题】Ipilimumab ( Yervoy ) was approved by the US FDA in 2011 for the treatment of melanoma . It is a monoclonal antibody that works to activate the immune system by targeting __________, a protein recepto...
A.
cytotoxic T lymphocyte-associated antigen 1 (CTLA-1)
B.
cytotoxic T lymphocyte-associated antigen 2 (CTLA-2)
C.
cytotoxic T lymphocyte-associated antigen 4 (CTLA-4)