Fig. 3. Distribution of microinjected labelled thymosin ß₄ in different cell lines. (A,B) Ten slices of 28 µm thickness of a continuous Z-scan one hour after microinjection of labelled thymosin ß₄ into NIH 3T3 cells; note its presence in the cytoplasm and its accumulation within the nucleus. (C-E and F-H) NIH 3T3 cells fixed 30 minutes after microinjection with 4% paraformaldehyde (C,F) and counterstained with TRITC-phalloidin (D,G); note the high concentration of labelled thymosin ß₄ within the cytoplasm and its colocalisation along the stress fibres (yellow in merged images E,H). (I-K) MCF-7 cell fixed 30 minutes after microinjection of labelled thymosin ß₄ (I) and counterstained with TRITC-phalloidin (J), with the merged image (K); note the almost even distribution between cytoplasm and nucleus. (L-N) Microinjection of labelled thymosin ß₄ into a single A431 cell grown within a cell cluster: preferential staining of the nucleus after two hours (L), phase-contrast image (M) and merged image (N). Insert in L shows nuclei of microinjected cells at higher magnification; note that the nucleoli appear almost unstained. Bars, 20 µm.