Heritable variations in growth potential and morphology within a clone of Balb/3T3 cells and their relation to tumor formation.

A nontransformed clone and a spontaneously transformed clone were isolated from a twice-recloned line of Balb/3T3 cells. At different times two sublines were initiated from the nontransformed clone, and three were initiated from the transformed clone. The sublines were maintained in parallel passages under the same conditions. Each subline was distinctive in appearance and fell into the same rank order in a variety of growth parameters in vitro. Colony formation in agar and tumor formation in mice occurred only in the morphologically transformed sublines, but there was no quantitative correlation between the two properties or with the rate of glucose utilization. Two of the cell populations derived from noninbred NIH nude mouse tumors of the 3 transformed sublines differed in agar colony formation from the parental sublines. The results indicate that there is an immense capacity for variation in cultured animal cells involving many unrelated characteristics expressed in a way that is difficult, if not impossible, to explain by conventional genetic models.