SLC38A4 and neoplasm: While the exact transporters involved in serine uptake within tumours remain incompletely defined [15], members of the solute carrier (SLC) superfamily, such as SLC1A4 (ASCT1) [16], SLC1A5 (ASCT2) [15, 17, 18], SLC7A10 [19], SLC38A2 [20], SLC38A4 [14] and SLC38A5 [14], have been implicated.