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Fig. 1. De novo keratin filament polymerization. To test the capability of the
EGFP-K5 fusion protein to form a functional keratin filament network, human
lens cells (which otherwise do not express keratins) were transfected with
either EGFP-K5/K14 pcDNA3 (A, B) or K5/K14 pcDNA3 (C,D) constructs (see
Materials and Methods). At day 1 after transfection a perinuclear ring of
keratin filaments is formed in both cases (A, C). At day 2, a keratin filament
network is formed in lens cells transfected with the K5/K14 pcDNA3 constructs
(D). Extended network formation with the EGFP-K5/K14 pcDNA3 constructs was
slightly slower, but by day 3 (B), the network produced was indistinguishable
from that of the K5/K14 pcDNA3-transfected cells.