LTB4R and esophageal squamous cell carcinoma: Therefore, the expression pattern of the two leukotriene B4 receptors LTB4R and LTB4R2 and the two receptors for cysteinyl leukotrienes (CYSLTR1 and CYSLTR2) was studied by immunohistochemistry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) in a prospective study cohort of patients with esophageal squamous cell cancer.