Fig. 1.

Strategy for developing syngeneic tumor lines with orthotopic growth potential. a Example of a genetic background that could be used for primary tumor formation. This animal harbors a Cre-inducible tumor-initiating oncogene (Kras^LSL-G12D), a Cre-deletable tumor suppressor (p53^flox), and a tracking allele (ROSA^mTmG). Homozygous or heterozygous tumor suppressor deletion can promote tumor formation depending on the tumor suppressor. b Example of a primary adenocarcinoma showing recombination of the ROSA^mTmG tracking allele. Tumor cells express mGFP while the surrounding non-recombined lung expresses mTomato. c Workflow for producing cell lines capable of orthotopic tumor growth. Detailed procedural details are included in the methods. d Outcome of attempts to establish cell lines capable of orthotopic tumor formation. There was no discernable pattern or marker that predicted which tumors were likely or unlikely to successfully move through the various stages of development other than establishment of a first passage tumor