However, in future studies the in situ technique could be used, instead of laser microdissection, to explore late branching events during tumor evolution, such as the recently described emergence of KRAS mutated clones during anti-EGFR treatment of KRAS wild-type colorectal carcinoma [23], expansion of clones with resistance mutations in EGFR-treated lung carcinoma [24], and development of secondary mutations during mTOR (mammalian target of rapamycin) inhibition in renal cell carcinoma [25]. This evidence concerns the gene KRAS and lung carcinoma.