It has been shown that PZR ITIMs can act as substrates for c-Src, c-Fyn, c-Lyn, Csk, and c-Abl [20], and that PZR, as well as other c-Src substrates (including FAK) in its close proximity, can become hyper-tyrosine phosphorylated in Noonan and LEOPARD syndrome murine models [16,17]. This evidence concerns the gene PTK2 and Noonan syndrome with multiple lentigines.