Adhesion to SP-A and MBL is α₂β₁ integrin-dependent. (A-B) Adhesion of WT and KO PMCs, either untreated or stimulated with PDB (40 nM), to SP-A, MBL, or BSA, as indicated, in the presence of 2 mM MgCl₂. All results are presented as mean ± SEM from triplicate wells of a single experiment and represent 1 of at least 3 experiments demonstrating similar results.