Biologically active NmU induces intracellular Ca⁺⁺flux in K562 cells. The time course of the intracellular Ca⁺⁺ flux response to the NmU peptide was performed as described in “Materials and methods.” The solid black arrows indicate the addition of NmU or ionomycin to Indo-1–labeled K562 cells. The results are representative of 5 independent experiments.