NTRK1 and mesothelioma: Thus, to identify receptor tyrosine kinases (RTKs) activated by progranulin in mesothelioma cells, we used an unbiased approach by testing antibody arrays that simultaneously assess tyrosine-phosphorylation levels of 49 different human RTKs and exposed these arrays to lysates derived from unstimulated (SFM) or progranulin-stimulated MSTO-211H or NCI-H2052 cells.