Figure 2. mECK^null.rK exhibit variable tumorigenicity.

(A) A graph depicting number of colonies formed in soft agar at 4 weeks from 5000 single cells originally plated. Error bar represents standard deviation of number of colonies counted in 10 separate fields imaged at 10×. NIH 3T3 cells and mECK^null cells do not form appreciable colonies while mECK^null.rK and mECK^null. rK133 cells exhibit robust colony formation. Error bars represent the SD between triplicate wells. (B) Representative image at 10× magnification of colonies in soft agar taken 4 weeks after plating single cell suspensions of NIH3T3, mECK^null, mECK36, mECK^null.rK and mECK^null. rK133. (C) Graph depicting mECK^null.rK tumor kinetics in athymic nu/nu mice. 3×10⁶ mECK^null.rK cells were subcutaneously injected into the hind flanks of 7 athymic nu/nu mice. 8 weeks later solid tumors were palpable in 4 of the 7 mice. Growth was monitored by caliper measurement.