HYAL2 and brain injury: The HYAL-2/WWOX/SMAD4 complex plays a critical role in hyaluronan or TGF-β1-mediated cell proliferation or apoptosis [26,44], neuronal death during traumatic brain injury in vivo [15,18,19,44], and activation of cytotoxic HYAL-2+ CD3− CD19− Z lymphocytes in vivo [50,51,52,53,54].