EIF4EBP1 and infectious otitis media: Consistent with these results, immunohistochemistry for phosphorylated S6 (pS6) and phosphorylated 4EBP1 (p4EBP1), which are downstream molecules of the mTORC1 pathway, as well as pSTAT3, revealed activation of both mTORC1 and IL6/JAK/STAT3 pathways in AOM/DSS-treated Rbbp9-/- tumors (Figure 4D–F).