MAPK3 and infection: The Erk/MAPK kinase (MEK) inhibitor U0126 was added for the first 3 hrs of infection (0–3 hpi; to prevent the first wave of Erk1/2 activation) or for the last 4 hrs of infection (8–12 hpi; to prevent the second wave of Erk1/2 activation), and fgf2 transcription was assessed at 12 hpi.