SLC19A1 and cancer: Nonetheless, potential interaction between folate levels and genotype at IKZF1 warrants further investigation since: i) transcription of the reduced folate carrier (SLC19A1) can be modulated by the balance of Ikaros activating and dominant-negative isoforms [26] and ii) increased circulating un-metabolised folic acid has demonstrated association with reduced natural killer cell cytotoxicity [27] which is in turn associated with cancer [28].