Under the pressures of the core-mantle boundary (2900km below the surface), the main constituent of the deep mantle, silicate perovskite, undergoes a phase transition to a post-perovskite phase whose mechanical properties remain unknown. A recent study published in Science shows the development lattice preferred orientations in an analogue of silicate post-perovskite plastically deformed above 100 GPa. The experiments were carried out inside a diamond anvil pressure cell and the measurements performed using x-ray diffraction at the HPCAT. It is found that (100) and (110) slip dominate the plastic deformation of post-perovskite. The contribution of post-perovskite to shear wave splitting should range from 0.1 to 3.1% for waves traveling in the plane of shear. In agreement with recent seismic observations of tilted transverse anisotropy in D”, for silicate post-perovskite the polarization anisotropy is usually inclined by about 45 degrees compared with the plane of shear. These results underline the importance of high-pressure experimentation in assessing plasticity and seismic anisotropy in the deep Earth.