MBNL1 and myotonic dystrophy type 1: The increase in MBNL1 protein level observed with the RNAi mediated PACT reduction in DM1 fibroblasts (Fig 3) was somewhat unanticipated given that while there may be shift in cellular compartmentalization of MBNL1 from foci to the nucleoplasm, total cellular MBNL1 would not be expected to change.