Fig. 4. Activated satellite cells show nuclear localisation of Act-β-Cat with Wnt1 but not Wnt6. Isolated fibres were cultured in the presence of Wnt1, Wnt6 or control cells for 2 hours. (A,D,G,J) Satellite cells following culture with Wnt1. (A) Robust expression of Act-β-Cat (green arrowhead). (D) Robust expression of MyoD (red arrowhead). (G) Colocalisation of Act-β-Cat and MyoD (white arrowhead). (J) Confocal slice-scan between points indicated by asterisks in G showing nuclear colocalisation of MyoD and Act-β-Cat. (B,E,H,K) Satellite cells following culture with Wnt6. (B) Weak expression of Act-β-Cat (green arrowhead). (E) Robust expression of MyoD (red arrowhead). (H) Mutually exclusive expression of Act-β-Cat (green arrowhead) and MyoD (red arrowhead). (K) Confocal slice-scan between points indicated by asterisks in H showing Act-β-Cat localisation flanking nuclear MyoD. (C,F,I,L) Satellite cells following culture with control cells. (C) No expression of Act-β-Cat in satellite cells (green arrowhead) but weak expression in adjacent myonuclei (blue arrowhead). (F) Robust expression of MyoD in satellite cell (red arrowhead). (I) Myonuclei express Act-β-Cat (green arrowhead) whereas satellite cells express MyoD (red arrowhead). (L) Confocal slice-scan between points indicated by asterisks in I showing no Act-β-Cat expression in the MyoD-positive satellite cell. (M) Quantification of BrdU⁺ Act-β-Cat⁺ satellite cell nuclei following 2 hours of culture in Wnt1, Wnt6 and LacZ control conditions. Myofibres exposed to Wnt1 conditions showed a significantly higher number of satellite cells expressing BrdU and nuclear Act-β-Cat (1.52±0.31) compared with LacZ controls (0.04±0.03), ^*P<0.0001, n=23 and n=27 myofibres for Wnt1 and LacZ, respectively. BrdU⁺ Act-β-Cat⁺ satellite-cell nuclei were never seen on Wnt6-treated myofibres (n=15 myofibres).