Therefore, in order to evaluate whether PPN could interfere with EGF-induced actin polymerization in OSA cells characterized with high functional levels of EGFR, we treated serum-starved MG-63 cells with PPN for 1 h and then stimulated the cells for 20 min with EGF (see "Methods" section). Here, EGFR is linked to obstructive sleep apnea syndrome.