Synaptotagmin IV (syt IV) expression is increased by forskolin. Control and syt I knockdown cells were treated with 50 μM forskolin (fsk) for 0, 2, 4 and 6 hours. (A) Immunoblot analysis shows that syt IV expression is upregulated after continuous fsk treatment for 4 hours in control PC12 cells. β-actin expression remained constant, and was used as a loading control. All lanes were loaded at 20 μg/lane. Syt IV expression was normalized to arbitrary densitometry units of β-actin measured in control PC12 cells (B), n = 7, and in shRNA-syt I knockdown cells (C), n = 4. Syt IV expressed peaked at 4 hours in both cell types (*p < 0.05).