CD4 and neoplasm: The physiological significance of distinct lactate transporter expression by CD4+- and CD8+-activated T cells might dictate their functional and migratory responses depending on the nature of the inflammatory exudate (i.e., more lactic acid versus sodium lactate) and underlay the differential distribution of these T cell subsets in the inflamed tissue, as it has been described in tumours and CIDs [42–44].