Deletion of either EF-hand domain of MCFD2 markedly decreases its interaction with FV and FVIII. COS-1 cells were cotransfected with the wild-type or the EF hand deletion mutants along with either FV (A) or FVIII (B). Cells were incubated with or without DSP before lysis. Cell lysates were immunoprecipitated with anti-myc (myc), anti-LMAN1 (L), and anti-MCFD2 (M).