SCF-induced proliferation of Lyn-deficient mast cells is reduced.

(A) SCF-induced DNA synthesis of Lyn-deficient mast cells is reduced compared to wild-type control cells. Bone marrow–derived mast cells from wild-type (■) and Lyn-deficient (░) mice were incubated for 60 hours in QBSF-58 media in the presence or absence of murine SCF (100 ng/mL). SCF-induced [³H]-thymidine incorporation was assessed as described in “Materials and methods.” All data represent the mean and standard deviation of quadruplicate samples. (B) PMA-induced growth of Lyn-deficient mast cells is normal. Bone marrow–derived mast cells from wild-type (■) and Lyn-deficient (░) mice were incubated in media or PMA (250 ng/mL). SCF-induced [³H]-thymidine incorporation was assessed as described in “Materials and methods.” All data represent the mean and standard deviation of quadruplicate samples.