SL-327 is a cell-permeable vinylogous cyanamide that acts as a selective inhibitor of MEK-1 and MEK-2 (IC50 = 0.18 and 0.22 μM respectively). SL-327 has been shown to block hippocampal LTP via inhibition of the MAPK/ERK cascade, which prevents CREB and Elk-1 phosphorylation, and LTP-dependent gene induction, resulting in rapidly decaying LTP, while being uncompetitive with respect to ATP. Brain penetrant in vivo, blocking fear conditioning and learning in rats, and producing neuroprotection in mice, following systemic administration. SL-327 has also been shown to inhibit ERK1, MEK-3/p38, MEK-4, JNK, and PKC activities when used at higher concentrations.