The end products of kinase activity include: activated proteins, inactivated proteins, modified carbohydrates, and signaling molecules. Kinases target and phosphorylate proteins, leading to protein activation. For example, the MAPK pathway is activated by the phosphorylation of different protein kinases, generating the activation of transcription factors and gene expression. Certain kinases may also act to inhibit protein activity. For example, glycogen synthase kinase-3 (GSK-3) phosphorylates and inactivates glycogen synthase.
Signaling molecules are another end product in kinase activity. Kinases may activate phospholipids and second messengers, causing the activation of downstream signaling pathways. For example, PI3K phosphorylates PIP2 to create PIP3. This in turn activates downstream signaling pathways involved in proliferation and cell survival.