To explore whether -26-exon FAK expresses in available breast tumor cell lines such as BT-474, MCF-7, the percentage of -26-exon FAK expression was determined using the strategy as described in Figure 1D and E. It is interesting to find that the signals of -26-exon FAK expression were observed in breast tumor cell line BT-549 and HCC1937 (Additional file 1: Figure S4). Here, PTK2 is linked to breast neoplasm.