Figure 5

Serum or BSA blocks release of PGK1 and LDH. HeLa cells were grown for 24 h in MEM containing 10% serum. After 24 h, media was removed, the cells washed with MEM containing the indicated amounts of serum (A) or BSA (B), and then incubated with the same media for 7.5 min. The media was collected and the amount of PGK1 and LDH was quantified as described in Materials and Methods. Values are expressed as the ratio of the amount of each protein in the media at each concentration of serum or BSA relative to that in the absence of serum or BSA, respectively. For graphing purposes, the sample lacking serum was defined as 0.001% serum and that lacking BSA as 0.01 mg/ml BSA. Error bars represent the s.d. of the mean (n = 4).