SHH and malignant pleural mesothelioma: The functions of the SHH signaling pathway have been previously explored in various types of human tumors, including B-cell lymphoma [22], malignant pleural mesothelioma [23], medulloblastoma [24, 25], pancreatic cancer [26, 27], prostate cancer [28, 29], lung cancer [30, 31], basal cell carcinoma [13], and chronic myelogeneous leukemia [32].