UNC3133 is a potent and selective Mer tyrosine kinase (MerTK) inhibitor with IC50 Mer 3.0 nM; Axl 17nM; Tyro 3.31 nM; FLT3 6.6 nM; PO Cmax = 0.023; IV T1 2 = 1.59 h, %F = 16. Mer tyrosine kinase (MerTK) is aberrantly elevated in various tumor cells and ha