Previous studies highlighted the involvement of DNA methylation in the regulation of the SLC44A4 and SLC34A2 in colon adenocarcinoma, renal cell carcinoma, small-cell lung cancer, and papillary thyroid carcinoma (Ricketts et al., 2012; Xue et al., 2018; He et al., 2020; He et al., 2022). Here, SLC44A4 is linked to small cell lung carcinoma.