Figure 4.

EGFR mutations L858R, T790M, and A702V promote ligand-independent growth. Ba/F3 cells were infected with lentiviral vectors encoding the indicated EGFR variants and cultured in the presence (A) or absence (B and C) of exogenous IL-3. Cell viability was measured by MTT analyses. A, all cell lines were viable in the presence of IL-3. B, after initial withdrawal of IL-3, cells expressing activating mutations emerged as IL-3–independent after a refractory phase of 7–14 days. C, after initial establishment of IL-3 independence, cells harboring activating mutants readily proliferated in the absence of IL-3. Error bars, S.D.