KRAS and neoplasm: Also, the less responsiveness to some tumor lines might be due to an aberrant expression of molecules typically associated with resistance to anti-HER1/2 targeting therapies such as c-Met, which is expressed in A431 tumor line [31], IGF-1R, expressed in SKBR3 tumor line [32], or another HER family members like HER3, overexpressed in SKBR3 tumor lines [33], as well as mutations driving constitutive activation of downsignalling cascades like KRas isoform detected, in A549 line [34].