Wei et al[26] found that miR-20a, miR-106b, and miR-17-5p were upregulated in nonfunctioning metastatic PC compared to the primary neoplasm and in metastatic PC and atypical PAs compared to typical PA; the involvement of these miRNAs in tumor progression was attributed to inhibition of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and TIMP-2. This evidence concerns the gene TIMP2 and pachyonychia congenita.