CCR7 and Langerhans cell histiocytosis: Similarly to LCH, an impaired adhesion and motility towards CCR7 was first reported for CML cells (14, 205) though this effect remains controversial since more recent reports showed in vitro and in vivo how a positive activation loop between BCR-ABL and the signal-transducing adaptor protein-2 (STAP-2) led to enhanced ERK signaling resulting in overexpression of CCR7, LN enlargement, and hepatosplenomegaly (203, 204).