Anti phospho erk p42 p44

Whole cell extracts were collected from C2C12 or BRITER cells in complete lysis buffer (20 mM Tris, 150 mM NaCl, 50 mM NaF, 1% NP40 substitute, HALT protease inhibitor cocktail (ThermoScientific). Proteins were resolved by electrophoresis on pre-cast 10% NuPage Bis-Tris gels (Invitrogen) and transferred to PVDF membranes (Bio-Rad). Membranes were blocked in 5% BSA-TBS-0.5% Tween-20 for 15 minutes, then incubated at 4° overnight with primary antibodies. Antibodies used were: rabbit anti-phospho-p38 MAPK (cat. no. 9211), anti-p38 MAPK XP (8690), anti-phospho-SMAD1/5 (9516), anti-SMAD1 XP (6944), anti-phospho-SMAD2/3 (8828), anti-SMAD2/3 XP (8685), anti-phospho-JNK (4668), anti-SAPK/JNK (9252), anti-phospho-Akt XP (4060), pan anti-Akt (4691), anti-phospho ERK p42/p44 (4377), anti-ERK p42/p44 (9102), anti-phospho-MKK3/6 (12280), anti-MKK3 (8535), anti-phospho-TAK1 (4531), anti-TAK1 (5206), anti-HA (3274), and anti-FLAG (14793); all from Cell Signaling); and mouse anti-p38α (cat. no. 33-1300), anti-p38β (33-8700; both ThermoFisher) and anti-β-actin (Sigma A1978). Proteins were visualized with HRP-conjugated secondary antibodies (Bio-Rad) with WestPico (ThermoFisher) or Immobilon (Millipore) chemiluminescence reagents. Images were obtained and analyzed for relative densitometric relationships on a LI-COR C-DiGit scanner using Image Studio software.