Further interrogation of the FACS data showed that the tumour-infiltrating NK cells associated with 5-FU treatment did not express high levels of Kv1.3; hence, [18F]AlF-NOTA-KCNA3P was instead likely measuring increases in tumour-infiltrating Kv1.3-expressing CD4+ TEM cells (Figure 3D). Here, CD4 is linked to neoplasm.