c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein kinases (MAPKs) family that are derived from three genes: Jnk1, Jnk2, and Jnk3. JNKs have been implicated in several cellular responses to homeostatic insults, including inflammation and apoptosis. We previously reported in a chronic epilepsy rat model significant elevated levels of phosphorylated JNKs (pJNKs), which indicate increased JNK activities. Additionally, we demonstrated that pharmacological manipulations of JNK proportionally affected seizure frequency. In this set of experiments, we attempted to identify which of the JNK isoforms (JNK1, JNK2, JNK3) contribute to the overall increased pJNK levels in our animal model of epilepsy. This would provide us insights as to the role(s) of JNKs in this disease. We measured the phosphorylation levels of the individual isoforms after pJNK enrichment from the CA1 hippocampal tissue of chronic epileptic rats and their age controls. The amount of protein was normalized by pJNK levels between experimental and control samples. We found a significant increase in activation levels of JNK2 in chronic epilepsy at 130 ± 9% (n=6, p=0.018) when compared to naïve, nonepileptic controls but insignificant changes in activation levels of JNK1 (97 ± 14%, n=5, p=0.83) and JNK3 (98 ± 17%, n=6, p=0.92). Previously, we had found in rats that JNK1 predominantly exists in the 46kDa size; JNK3 predominantly exists in the 54 kDa; and JNK2 exists in both sizes equally. We further analyze which of the JNK bands (46 kDa and 54 kDa or both) contribute to the elevated phosphorylated JNK levels. Given the previous pharmacological observation that JNK manipulation does influence seizure frequency in epilepsy, this investigation is imperative as it will allow us to narrow our focus to a specific JNK isoform to study further.