FIGURE 8:

Calpains are present in α2-MVBs. Immunoblot labeling of calpain-1 and α2 integrin from SAOS-α2β1 cell lysates (lys) or after immunoprecipitation was performed. Immunoprecipitation of total α2 or β1 integrin pool from cell lysates with or without α2 integrin clustering was performed with polyclonal α2 integrin (pAb, ab1936) or monoclonal β1 integrin (mAb, 12G10, and Mab13) antibodies. A pool of clustered α2β1 integrins was specifically precipitated with the rabbit anti-mouse (r.a.m.) antibody that was used for clustering of the α2 integrin mAbs (MCA2025, A211E10, A2E). The 80-kDa and a smaller form of calpain-1 are indicated by arrows.