This image shows a cortical neuron from an embryonic day 14 wild-type mouse grown in culture for 7 days. The cell was immunostained with antibodies against phosphorylated Src/Fyn (pY527, green), Src (red), and the microtubule-associated protein MAP2 (blue) antibodies. The pY527 signal is localized in dendritic growth cones. Sema3A stimulation decreases the pY527 signal in wild-type neurons, but not in those lacking the protein tyrosine phosphatase Ptpδ. For more information, see the article by Nakamura et al. (pages 7125–7139).