LCK and pulmonary arterial hypertension: Based on a high-throughput (HTS) siRNA screen of ~ genes, using a BRE reporter mouse cell line with ID1 expression as readout for increased BMPR2 signaling, in combination with an analysis of publicly available PAH RNA expression data, our group previously identified clinically relevant novel BMPR2 signaling modifier genes, namely, fragile histidine triad (FHIT) [8] and lymphocyte cell-specific protein tyrosine kinase (LCK) [9].