Export of NPM mutants require 2 NES motifs. Confocal microscope analysis of NIH-3T3 transfected with either pEGFP-C1-NPMmA (left panel), pEGFP-C1-NPM_MUT_A_NO_1st_NES (middle panel), or pEGFP-C1-NPM_MUT_A_NO_2nd_NES (right panel). NPM mutant A containing both NES motifs localizes in the cytoplasm. Disruption of either N-terminal (middle panel) or C-terminal (right panel) NES motif in the NPM mutant A impedes nuclear export of the protein that appears localized in the nucleoplasm (middle and right panels, bottom). Images were collected as described²⁷  using a Zeiss Plan Apochromat 100 ×/1.4 NA oil objective.