Since the ACE2 gene expression in the tongue squamous cell carcinoma cell line HSC3 and the TMPRSS2 gene expression in the human glioma cell line LN319 were established by a microarray, HSC3 and LN319 were used as experimental controls of the RT‐PCR analysis for the ACE2 and TMPRSS2 gene expression in the human tissue specimens. Here, ACE2 is linked to central nervous system cancer.