This family represents the C-terminal region of merozoite surface protein 1 (MSP1) which are found in a number of Plasmodium species. MSP-1 is a 200-kDa protein expressed on the surface of the P. vivax merozoite. MSP-1 of Plasmodium species is synthesized as a high-molecular-weight precursor and then processed into several fragments. At the time of red cell invasion by the merozoite, only the 19-kDa C-terminal fragment (MSP-119), which contains two epidermal growth factor-like domains, remains on the surface. Antibodies against MSP-119 inhibit merozoite entry into red cells, and immunisation with MSP-119 protects monkeys from challenging infections. Hence, MSP-119 is considered a promising vaccine candidate.