Receptors that mediate this process trigger both a fast, excitatory signal and a slow, inhibitory signal according to the LEGI model. Receptors that facilitate this process (-5[1])are divided into three families based on whether there are 0, 1, or 3 (15[1])amino acids between their two N-terminal cysteines. Pro-inflammatory formyl peptides like fMLF mediate pattern recognition and this process. (-5[1])Leu·ko·tri·ene B4, complement protein (-5[1])5a, (15[1])and inter·leu·kin 8 are the (-5[1])main (-5[1])mediators of this process in (-5[1])neutrophils. HIV (*) enters T-cells and macrophages (-5[1])by hijacking two co-receptors that mediate this process, (-5[2])called CCR5 and (-5[1])CXCR4. (10[1]-5[4])Many immune cells use a gradient-sensing (-5[1])form of this (10[1])process to target sites of foreign invasion. For 10 points, name this process in which a cell moves in (10[1])response (10[2])to a chemical (10[1])stimulus. (10[1])■END■ (10[13]0[1])