LTP-Related Gene Networks Figure 6. IPA Categorization of LRG sets according to their Canonical Pathways. doi:10.1371/journal.pone.0040538.g006 emerging theme of negative regulation of gene expression is further exemplified in a later highly significant network (5 h Network 4: Score 21; Figure 7D), where ubiquitin forms a central hub. This network predicts an LTP-associated increase in protein degradation which is mediated by upregulation of TOLLIP, (Tol interacting protein), a molecule which forms part of a complex which promotes endosomal trafficking of clathrin and ubiquiti- nated proteins to endosomes [45], and the ubiquitin-conjugating enzyme, UBE2G2 [46]. 3.3 Dynamic epigenetic regulation of LTP-related gene expression. In 5 h-Network 2 (Figure 7B; Score 33) the microRNA MIR24-1 formed a hub, while MIR34A is present PLoS ONE | www.plosone.org 7 July 2012 | Volume 7 | Issue 7 | e40538