CCR5 and cancer: Taken together, the results suggest that our pNK cells with a high expression of CD40L and CCR5 may induce high cytotoxic effects on CD40-high cancers, such as melanoma, breast, and head and neck cancers [31, 32], or CCL5-high cancers, such as ovarian, metastatic breast, cervical, and gastric cancers [33, 34].