Other reports have showed that CD44+ status along with CD117+ is a marker of ovarian cancer-initiating cells [63], while when CD44+CD117+cells were compared using two-dimensional (2D) culture versus a three-dimensional (3D) culture system, CD44+CD117+ cells possessed not only the CSC properties, but also exhibited increased chemoresistance in 3D compared to 2D culture, suggesting a more relevant model for studying CSC response to anticancer drugs [64,65]. Here, CD44 is linked to ovarian cancer.