SMAD4 and skeletal muscle disorder: Overexpression of PIAS1, with vector only, or with wild type or SUMO loss of function mutant Smad4, in rat hippocampi in vivo supported the idea that Smad4 SUMOylation on Lysines 113 and 159 in rodent hippocampus promotes gene expression of the skeletal myopathy gene tropomyosin 2 (TPM2), and improved memory formation and spatial learning [64].