Kos1, a nonreceptor tyrosine kinase that suppresses Ras signaling.

Kinase of embryonic stem cells (Kos1), a nonreceptor protein tyrosine kinase (NRPTK), was identified and cloned from differentiating murine embryonic stem cells. Kos1 is localized on mouse chromosome 11 that corresponds to human chromosome 17p13.1 and is homologous to Tnk1, Ack1 and Ack2, making it a new member of the Ack family of NRPTKs.