Fundamental plane as a function of redshift for central ETGs from Horizon-AGN (left panel) and Horizon-noAGN (right panel). The magenta, blue, red, green, and yellow lines depict the simulated relations at z = 0, z = 0.5, z = 1, z = 2, and z = 3, respectively. The regions between the 25 and 75% are shaded. The virial relation for galaxies at z = 0 (black solid line) is included. For comparison, the observational results from ATLAS^3D are indicated in black crosses.