Fig. 4

Progesterone and doxycycline have an additive effect on the reduction of active and latent MMP-2 levels. a 12Z endometriosis cells with either 10 nM progesterone (Prog) or 1 μg/ml doxycycline (Dox) or the simultaneous combination of both substances. The combination of low-dose doxycycline (1 μg/ml) with progesterone (10 nM) showed an additive effect on the reduction of active MMP-2. b Already at a low dose (1 μg/ml) doxycycline shows an additive effect to progesterone (10 nM) on inhibition of pro-MMP2. The results are represented as mean ± SD