Fig. 1.
Regulation of PIM expression at the mRNA and protein levels. In the presence of cytokines and growth factors, cytokine receptors and RTKs induce the transcription of PIM isoforms through various transcription factors, and in response to hypoxia, PIM2 is transcriptionally activated by HIF-1. At the protein level, PIM kinases are rapidly degraded by the proteasome under normal conditions. Dephosphorylation of PIM by PP2A and binding to HSP70 promote PIM ubiquitination and degradation, whereas PIM is stabilized in the presence of HSP90 and under hypoxic conditions.