Fig. 4.

Ca²⁺ is required to ensure β1-integrin folding and trafficking to the Golgi. HT1080 cells were starved and pulse-labelled for 30 minutes, and chased for up to 2 hours in the absence (A,C,E) or presence of thapsigargin (B,D,F). Cell lysates were collected at varying time points as indicated, β1-integrin immunoisolated with TS2/16 (A,B), 9EG7 (C,D) or JB1A (E,F) and then subjected to SDS-PAGE and autoradiography. The identity of radiolabelled proteins is as indicated in previous figures. Arrows indicate non-specific protein bands that were also pulled down by Protein-G–Sepharose alone (see Fig. 2).