Under normal growth conditions (no stress), small (S, 40S) and large (L, 60S) RPs are assembled in the nucleolus (NO) and transported to the cytoplasm (CP) for protein synthesis. Under nucleolar stress, ribosomal biogenesis is inhibited and Ribosome-free forms of RPs (RPL and RPS) enter the nucleoplasm (NP) to interact with MDM2, resulting in p53 stabilization and activation. Similarly, RPs either released from breaking down (indicated by wavy edges) of cytoplasmic Ribosomes or overproduced in the cytoplasm can enter the nucleoplasm to interact with MDM2.