Fig. 1

Generation of mouse hybridomas by fusions of immortal thymidine kinase(tk)-less mouse myeloma cells with normal mouse B-cells in about 50% polyethylene glycol [26, 35, 36]. After fusions of 5 to 10 min immortal myeloma-B-cell hybrids or hybridomas survive in the presence of the inhibitor of DNA synthesis aminopterin on supplemental thymidine picked up by B-cell-derived kinase. The majority of fused cells die from defective cell walls randomly denatured by polyethylene glycol or from non-proliferative chromosome combinations without myeloma-specific immortalizing chromosomes and or from lack of chromosomes with B-cell specific kinase