Fig. 7. CaM kinase IV activity in human sperm. CaMKIV activity was measured in sperm treated immediately after resuspension in the Ca²⁺-containing medium (T0) or in sperm incubated in the same medium for 18 hours in the absence (T18) or presence of 60 µM KN62 [T18 (KN62)]. Sperm subjected to these different experimental conditions were washed twice with PBS, cell concentration was adjusted to 10⁷ cells/ml, and aliquots were stored at –20°C until use. Enzyme activity was measured in these extracts using peptide gamma and [-³²P]ATP as substrates. The results are expressed as mean±s.e.m., n=7. *P<0.001 compared to CaMKIV activity in T0 and T18 (KN62) cells; **P<0.01 compared to CaMKIV activity in T0 and T18 cells.