MID1 and acrocallosal syndrome: Interestingly, GCPS- and acrocallosal syndrome-associated point mutations within the MID1-α4-PP2A complex-dependent interaction domain led to a misregulation of the subcellular localization, a loss of the MID1-α4-PP2A complex-dependent nuclear localization of GLI3, and a reduction of the transcriptional activity of mutant GLI3.