SLC22A4 and cancer: The expression of OCTN1 has been investigated in the non-small cell lung cancer cell line A549 in comparison with other cell lines (Figures 1A, B), prototypes of aggressive cancers, most of which are also known to rely on non-neuronal ACh signalling (Parnell et al., 2012; Friedman et al., 2019; Aronowitz et al., 2022; Zhang et al., 2020); HEK293 was employed as control due to the relatively low level of OCTN1 expression (Tamai et al., 1997; Drenberg et al., 2017; Tamai et al., 2000).