Figure 4

Tamoxifen induces Src-kinase activity in E-cadherin-deficient MCF-7 cells. (a) MCF-7 cells were treated with plain medium ('C'), transfection lipid ('L'), non-targeting siRNA ('NT') or CDH1 siRNA ('CDH1') for 72 hours before culture in oestrogen-free or tamoxifen-containing medium. Cells were lysed then immunoprobed for activated Src (Src phosphorylated at Y418), total Src (pan Src) and Glyceraldehyde-3-Phosphate Dhydrogenase (GAPDH). (b) Replicate immunoprobings were scanned and the data normalised to semi-quantitate the effects of tamoxifen or oestrogen withdrawal on Src activity in the absence of E-cadherin. siRNA-mediated inhibition of E-cadherin combined with tamoxifen caused an increase in the levels of phosphorylated Src detectable in these cells. *p < 0.05 versus untreated cells.