Derivation of the 4102 tumor cell lines. Derivation of the 4102 tumor cell lines. The primary 4102 tumor arose in a C3H mouse chronically exposed to UV light. Two separate fragments were adapted to culture to generate the PRIM1 and PRIM2 cell lines. The PRIM1 cell line was used to generate more progressive tumors by serial passage first in a C3H nude mouse and then in immunocompetent mice. In the first transplant generation, the tumor grew progressively in only one of ten normal mice; in subsequent transplant generations, the tumor grew progressively in every mouse. The LatePRO cell line was established after the fourth transplant generation. Terry H. Wu et al. Cancer Immun 2011;11:2 Copyright © 2011 by Terry H. Wu