PTK7 and neoplasm: Figure 6B showed the PTK7 were successfully silenced by PTK7-specific siRNA. Tumor sections of the xenografts were analyzed by hematoxylin and eosin staining followed by TUNEL and Ki67 staining (Figure 6C). The group treated with the PTK7 siRNA tended to have more TUNEL positive and less Ki67 positive cells than the scrambled siRNA group (Figure 6D).