SLC6A4 and pulmonary arterial hypertension: We have previously shown that normoxic female SERT+ mice develop spontaneous PAH at 5 months of age in an estrogen-dependent manner, while male SERT+ mice do not.11,16 In the SERT+ mice, the increase in RVSP and pulmonary vascular remodelling was abolished by MPP (Figure 4A–C).