Table 2. Specific activity of Gly-Pro-p-nitroanilide hydrolysis in absence (control) and in presence of sitagliptin phosphate 2mM, a DPPIV/CD26 inhibitor, and NEM 5mM, a DP-8 and -9 inhibitor, in the cell monolayer of keratinocytes and cervical cancer cell lines.

Cell line	Control (37°C, pH = 7.4)	Sitagliptin phosphate (37°C, pH = 7.4)	Control (room, pH = 8.0)	Sitagliptin phosphate (room, pH = 8.0)	NEM (room, pH = 8.0)
HaCaT	9.1± 0.1	0.8± 0.2*	8.0± 0.5	0.2± 0.1*	8.0± 0.4
SiHa	7.9± 0.1	2.6± 0.1*	6.0± 0.1#	0.1± 0.2*	5.7± 0.2
HeLa	4.0± 0.3	1.2± 0.1*	3.0± 0.2#	0.1± 0.1*	2.9± 0.2
C33A	3.7± 0.1	1.5± 0.1*	2.5± 0.2#	0.1± 0.1*	2.2± 0.3

Gly-Pro-p-nitroanilide hydrolysis was measured in immortalized keratinocytes (HaCaT) and in human cervical cancer cell lines (SiHa, HeLa and C33A) as described in Material and Methods. Mean values ± S.D is expressed in specific activity (nmol of p-nitroaniline liberated/min/mg of protein). The values are representative of three different experiments.

*Indicates statistical significance when the sitagliptin phosphate and NEM groups were compared to the respective control group.

^#Indicates statistical significance when controls were compared, indicating the effect of pH and temperature. ANOVA followed by Tukey’s test, p ≤ 0.05.