We further endogenously knocked down MFSD4A-AS1 expression and stably overexpressed MFSD4A-AS1 in B-CPAP and K1 cells, because these two cell lines showed moderate levels of MFSD4A-AS1 compared to other thyroid cancer cell lines (Supplementary Fig. 2B), and the tumorigenic role of K1 in animal experiment in vivo was markedly superior to other PTC cell lines based on our previous experiments. Here, KRT1 is linked to thyroid cancer.