Nuclear matter is dense, and the close proximity of nucleons may allow quarks in different nucleons to interact directly, leading to nucleon modification. Mean-field models predict that all nucleons experience some degree of structure modification, and they are consistent with the observation that the EMC effect increases with nuclear size, scales with local density, and saturates for very large nuclei. Furthermore, mean-field models also predict a large "polarized EMC effect": a large modification of the spin-dependent g 1 structure function for nuclei relative to that of their constituent protons and neutrons. This prediction will be tested experimentally using measurements of a polarized Li-7 target as part of the Jefferson Lab CLAS-12 program.