PEDF may inhibit PC growth and metastasis by downregulating transforming growth factor beta (TGF-β), signal transducer and activator of transcription 3 (STAT3), and androgen receptor (AR) signalling in order to control the expression of genes involved in apoptosis, cell cycle regulation, metastasis, and invasiveness in PC cells [42]. This evidence concerns the gene AR and pachyonychia congenita.