showed a trendP = 0.1581
Prolonged culture with old serum showed a trend of increased expression of telomerase reverse transcriptase ( TERT ) ( Fig. 7C-D , P = 0.1581) and of the neuron-specific enzyme ubiquitin carboxyl-terminal esterase L1 ( UCHL1 ) ( Fig. 7E-F , P = 0.0485).