Before revision:  We find that the cell deformation and cell rearrangement rate fields correlate strongly, which is compatible with a  viscoelastic liquid behaviour with a relaxation time \tau = 70 \pm 15 min.
After revision:  We find that the cell deformation and cell rearrangement rate fields correlate strongly, which is compatible with a Maxwell viscoelastic liquid behaviour with a relaxation time \tau = 70 \pm 15 min.