PTGES2 and melanoma: Furthermore, gene expression analysis of pre-treatment and post-progression biopsies from a published cohort of melanoma patients treated with the BRAF inhibitors vemurafenib or dabrafenib indicated that the mRNA expression of PTGES or PTGES2 as well as PC was increased in the tumours of some patients who experienced progressive disease (Fig. 6b).23 Therefore, it is conceivable that elevated PTGES/PTGES2 and/or PC expression may contribute to BRAF-inhibitor resistance in melanoma patients.