Impact of ectopic expression of <i>Src</i>^E527K in parental OE19 on lapatinib sensitivity and cell signalling.

<p><b>A,</b> Dose-response curves for lapatinib in the non-transduced parental OE19 (OE19 ^Mock), transduced with GFP (OE19 ^GFP), wild-type <i>Src</i> (OE19 ^{Src wild-type}) or <i>Src</i>^E527K mutation (OE19 ^{Src E527K}). The calculated values of IC₅₀ for lapatinib was >1,000 nM in OE19 ^{Src E527K} cells. Values were presented as relative cellular viability relative to vehicle-treated controls with the mean ± S.E. of quadruplicate from a representative experiment. The <i>p</i> value calculated by two-way ANOVA was 0.376 for mock <i>vs</i> control (GFP), <0.0001 for control <i>vs</i> wild-type Src, and <0.0001 for control <i>vs Src</i>^E527K. <b>B,</b> Relative cell viability lapatinib in the non-transduced parental OE19 (OE19 ^Mock), transduced with GFP (OE19 ^GFP), wild-type <i>Src</i> (OE19 ^{Src wild-type}) or <i>Src</i>^E527K mutation (OE19 ^{Src E527K}). The <i>p</i> values were calculated by two-tailed <i>t</i>-test. Values were presented as relative cellular viability relative to vehicle-treated controls with the mean ± S.E. of quadruplicate from a representative experiment. <b>C,</b> Immunoblots showing changes of various signalling proteins after treatment with 1 µM concentration of lapatinib or saracatinib, either alone or combination, in the OE19 cells with or without Src ^E527K transduction.