Fig 1. Number of positively SA β-Gal stained quiescent cells.

Percentage of positively stained SA β-Gal fibroblasts during short- (0, 7 and 14 days) and long-term (100 days) cultivation of quiescent BJ cells (black dots) transferred by contact inhibition (top) or serum starvation (bottom). After 14 and 100 days, cells were cultivated for 3 days in total under normal proliferating conditions (“recovered from G₀“; unfilled circles). Each data point represents a single experiment and the experimental error of all measured values is about ±10%.