Table 1. Population doubling times (in hours) of primary neonatal foreskin keratinocytes from three donors (A, B and C) cultured in various conditions.

Culture condition	Donor A	Donor B	Donor C
Control	38.1	38.2	41.6
Rapamycin	42.8	46.5	66.0
Y‐27632	30.1	31.6	30.3
Rapamycin + Y‐27632	39.6	44.5	49.1