Although the Ag that an Ab may target is unique, the method of producing various mAbs is very similar. The target Ag, or part of the Ag, is injected into a host animal that will then mount an immune response and create a pool of B cells specific to that Ag. The B cells are harvested and put into culture with myeloma cells, where the 2 cell types can be fused. After mitotic division, a hybridoma is created that can produce the desired mAb yet have the reproductive properties of the tumor cells. The result is a line of immortal mAb-producing cells that can divide in vitro to generate daughter cells and, therefore, more Abs. However, the Fc region of Abs produced in host animals, such as mice and horses, are recognized as foreign when given to humans. Consequently, an immune response can be initiated that can neutralize the treatment or even lead to a fatal anaphylactic reaction. Modern therapeutic lines of mAbs are often humanized through the use of transgenic mice that create Abs with human Fc regions. Products that use this method are identifiable as having names that end in -zumab. Another approach is to split host-derived mAbs and then combine the created Fv region with human Fc regions. The end products are considered to be chimeras and have names that end in -ximab. A third common approach is to create a fusion protein composed of a human Fc region and an Ag-specific receptor. These products may not resemble typical Abs in structure but act in a similar manner. Etanercept was one of the first approved products to use this approach, but more have since been created, and all share the -ceptsuffix. Despite the variety of methods used, the goal is to mass produce Abs that are specific to a desired Ag yet do not induce an immunogenic response against themselves.