- The germinal center kinase (GCK)-related protein kinases HPK1 and KHS are candidates for highly selective signal transducers of Crk family adapter proteins. Oehrl, W., Kardinal, C., Ruf, S., Adermann, K., Groffen, J., Feng, G.S., Blenis, J., Tan, T.H., Feller, S.M. Oncogene (1998)