PIN1 and neoplasm: Moreover, in unstimulated tumor cells, the mRNA decay-promoting factor KSRP was required for the rapid degradation of β-catenin transcripts [82] whereas p38 MAPK-mediated phosphorylation of KSRP at a Pin1 site (pThr692-Pro693) impaired KSRP-RNA interactions and increased target mRNA abundance [81], suggesting that KSRP phosphorylation is also crucial for its mRNA binding capabilities (Table 1 and Figure 1).