Subsequently, to verify the effect of miR-423-5p on GRAM2 expression, we determined the GREM2 levels in the PC cells treated with the CAF-derived exosomes, and the results showed that the GREM mRNA and protein levels in the PC cells treated with the CAF-derived exosomes were significantly decreased, while obvious changes were observed in the PC cells after exosomal miR-423-5p was decreased (P < 0.05, Fig. 5c, d). The gene discussed is GREM2; the disease is pachyonychia congenita.