Figure 3.

Phenotype of the primary 4102 tumor cells in vitro. (A) 4102 cell lines have abnormal DNA content. Cells fixed and permeabilized with ethanol were stained with propidium iodide and analyzed for DNA content by flow cytometry. Normal spleen cells were used as a diploid control. The PRIM2 and LatePRO cell lines were composed mainly of tetraploid cells and the PRIM1 cell line contained in addition 8% near diploid cells. (B) Morphology of 4102 tumor cells in culture. The primary tumor cells were very similar in appearance to normal fibroblasts in culture, and were easily distinguished from the LatePRO cells by their large size, flatness, and low refractivity. (C) The PRIM1 and PRIM2 cell lines failed to form colonies in soft agar. Clonogenicity of the tumor cell lines was determined by overlaying 100 tumor cells in 0.21% agarose atop a 0.26% agarose base layer and culturing for 10 days. The results are represented as the average cloning efficiency in four wells, calculated using the formula: cloning efficiency = (colonies greater than or equal to 0.05 mm in diameter / total colonies) x 100.