Inositol pentakisphosphate (abbreviated IP5) is a molecule derived from inositol tetrakisphosphate by adding a phosphate group with the help of inositol polyphosphate multikinase (IPMK). It is believed to be one of the many second messengers in the inositol phosphate

Inositol phosphate

Inositol phosphates are a group of mono- to polyphosphorylated inositols. They play crucial roles in diverse cellular functions, such as cell growth, apoptosis, cell migration, endocytosis, and cell differentiation.The group comprises:...

 family. It "is implicated in a wide array of biological and pathophysiological responses, including tumorigenesis, invasion and metastasis, therefore specific inhibitors of the kinase may prove useful in cancer therapy."

IP5 also plays a role in defense signaling in plants. It potentiates the interaction of the plant hormone JA-Ile

Jasmonate

Jasmonate and its derivatives are lipid-based hormone signals that regulate a wide range of processes in plants, ranging from growth and photosynthesis to reproductive development. In particular, JAs are critical for plant defense against herbivory and plant responses to poor environmental...

by its receptor.