ENPP1 and cancer: Although the performances of NUCB2, EPB41L4B, SEL1L, and ENPP1 were quite consistent, we observed an uneven distribution in PDK4 expression across these cell lines, meaning that the relation between PDK4 expression and miR-181a in tumour cells may not be causal, and the contribution of these pairs might come from other cell types, such as cancer associated fibroblasts or immune infiltrates.