41. Stimulation of CXCR1 in neutrophils by its primary ligand, Interleukin 8, leads to neutrophil chemotaxis and activation. 42. Brain-derived neurotrophic factor is among the chemotactic factors that stimulate Numb-mediated chemotaxis during cell migration. 43. Studies of this receptor and its ligands suggested its role in regulation of monocyte chemotaxis and thymic cell apoptosis. 44. Phytohaemagglutinin upregulates mRNA in circulating leukocytes; in these cells, TAAR1 activation mediates leukocyte chemotaxis toward TAAR1 agonists. 45. As in sperm chemotaxis , only capacitated spermatozoa are thermotactically responsive ( Bahat et al ., 2003 ). 46. Cancer metastasis is thought to be directly coupled to growth factor gradients that facilitate chemotaxis of cancer promoter factors. 47. Micromotors and nanomotors can also move preferentially in the direction of externally applied chemical gradient, defined as chemotaxis . 48. Since eggs release progesterone, sperm may use progesterone as a homing signal to swim toward eggs ( chemotaxis ). 49. Upon release from the germinated resting spore, zoospores seek out a suitable substrate for growth using chemotaxis or phototaxis. 50. Sperm cells also express odor receptors, which are thought to be involved in chemotaxis to find the egg cell.
