Producing monoclonal antibodies1. Mice are exposed to the non-self antigen for which the antibodies are required.2. The mouse B cells producing the required antibodies are extracted from the mouse spleen.3. The mouse B cells are mixed with cells from a cancer tumour so they will divide readily outside the body.4. Polyethylene glycol (PEG) is added to fuse the cell membranes of both types of cell together into a hybridoma.5. The hybridoma cells are separated under a microscope and each single cell is cloned.