FIG. 1.

Ras effector mutants stimulate colony formation in WRT cells. Cells were transfected with pDCR or pDCR encoding Ras^G12, Ras^V12, or GTPase-deficient (V12) forms of Ras^G37 and Ras^S35. Twenty-four hours after transfection, TSH-supplemented (+TSH) or -deficient (−TSH) medium containing G418 was added to replicate plates, and the cells were fixed and stained 21 days later. Colony size could not be evaluated in Ras^V12-transfected cells since these cells were morphologically transformed and did not form compact colonies. Four experiments were performed with similar results.