This is an announcement for the paper "On Grothendieck subspaces" by S. S. Kutateladze. Abstract: The modulus of an order bounded functional on a Riesz space is the sum of a pair of Riesz homomorphisms if and only if the kernel of this functional is a Grothendieck subspace of the ambient Riesz space. An operator version of this fact is given. Archive classification: Functional Analysis Mathematics Subject Classification: 46 B 42 The source file(s), sums.ams: 5318 bytes, is(are) stored in gzipped form as 0504046.gz with size 2kb. The corresponding postcript file has gzipped size 20kb. Submitted from: sskut@member.ams.org The paper may be downloaded from the archive by web browser from URL http://front.math.ucdavis.edu/math.FA/0504046 or http://arXiv.org/abs/math.FA/0504046 or by email in unzipped form by transmitting an empty message with subject line uget 0504046 or in gzipped form by using subject line get 0504046 to: math@arXiv.org.