Cells were lysed using a modified RIPA buffer (50 mM Tris (pH 8.0), 150 mM NaCl, 1.0% NP-40, 0.5% Sodium deoxycholate, 0.1% SDS, 10mM Na4P2O7, 10 mM β-glycerolphosphate, 10mM NaF, 10mM EDTA, 1mM EGTA) with 1X HALT phosphatase/protease inhibitor cocktail (Thermo) added prior to lysis as described [35 (link)]. The following antibodies were used: Sigma, anti-Cx43 (C6219); Cell Signaling Technology, total ERK (9102L), phospho-ERK (9101L), total PKCδ (2058S), phospho-PKCδ Thr505 (9374S), PCNA (2586S), anti-Rabbit HRP (7074S), anti mouse HRP (7076S); Millipore, GAPDH (MAB374) and anti-osterix (AB3743). Representative blots are shown and were repeated a minimum of two times.