Go J Yoshida *,Hideyuki Saya
It has recently been reported that molecular targeting drugs fail to overcome the ?oncogene/oncogenic signaladdiction? of cancer cells. Tumor tissue is composed of heterogeneous cancer cells, so that the therapeutic response is difficult to predict. Recent advance in cancer research has strongly suggests that cancer stem cells contribute to the formation and maintenance of the heterogeneous cellular society in the tumor tissue. After all, this heterogeneity is the major cause of the acquired resistance to anti-tumor therapies. In this commentary, we would like to briefly explain the promising therapeutic targets of CD44 variant isoform and EpCAM, the ?functional? cancer stem cell markers.