Inositol 1,4,5-trisphosphate may be a signal for f-Met-Leu-Phe-induced intracellular Ca mobilisation in human leucocytes (HL-60 cells).

Permeabilised, dimethyl sulphoxide-differentiated HL-60 human myelomonocytic leukemia cells accumulate 45Ca in an ATP-dependent manner. The 45Ca is taken up by a pool thought to be a component of the endoplasmic reticulum. Inositol trisphosphate induced a rapid release of Ca from this pool, suggesting that this molecule which is formed in these cells in response to f-Met-Leu-Phe may play a role in agonist-induced Ca metabolism.