PAK1 is required for

C albicans–induced MAPK activation in PMNs. (A) Kinase-deficient PAK1 and CD56-expressing PMNs were stimulated withC albicans for 0 to 5 minutes at 37°C. Whole-cell lysates were immunoprecipated with anti-PAK1 for analysis of PAK1 activity by an in vitro kinase assay with MBP as the phosphorylation substrate. After autoradiography, the same membrane was stripped and reprobed with anti-PAK1 to check for equal loading. (B) PMNs from the same aliquots were also tested for their ability to inhibit C albicansgrowth. (C) PMNs from panel B were also probed with antiactive MAPK, anti-CD56, or anti-panERK.