Fig. 4. Effect of CaM on protein tyrosine phosphorylation of mouse sperm components. Cauda epididymal spermatozoa were incubated in EKRB medium supplemented with 3 mg/ml BSA in the absence or presence of 10 µM CaM. After 90 minutes at 37°C under 5% CO₂ in air, sperm cells were pelleted, washed, extracted, resolved by SDS-PAGE, and protein-tyrosine-phosphorylated components were revealed as above. Bands from the exposed X-ray film were scanned and the intensities of control and CaM-treated groups quantified. The asterisk (*) indicates a significant difference (P<0.05) between the control and experimental groups.