MCFD2 missense mutations identified in F5F8D patients do not abolish crosslinking to FV and FVIII. COS-1 cells were cotransfected with the wild-type or indicated MCFD2 missense mutants along with either FV (A) or FVIII (B). Cells were incubated with or without DSP before lysis. Cell lysates were immunoprecipitated with preimmune serum (pre), anti-myc (myc), anti-LMAN1 (L), and either anti-FV (F5 in panel A) or anti-FVIII (F8 in panel B) antibodies.