TPBG and nasopharyngeal carcinoma: To ascertain whether 5T4-28Z-engineered CIK cells were capable of specifically recognizing and eliminating 5T4-positive NPC cells while maintaining their original antitumour activity, a series of functional assays were performed in which different effector cells were challenged in various ways with 5T4 low-expressing S18 and S26 cells as well as their spheroid cells that exhibited intermediate or high levels of 5T4 expression.