Suppresses the insulin receptor and EGFR-transduced MAPK signaling pathway, but does not inhibit MAPK activation by a constitutively active mutant Ras (PubMed:12027893). Probably impairs the formation of GTP-Ras (PubMed:12027893). Inhibits Ras-independent, but not Ras-dependent, activation of RAF1 (PubMed:12717443). Represses integrin-mediated cell spreading via inhibition of TESK1-mediated phosphorylation of cofilin (PubMed:15584898). {ECO:0000269|PubMed:12027893, ECO:0000269|PubMed:12717443, ECO:0000269|PubMed:15584898}. This is the function of ENSG00000187678 (SPRY4, sprouty RTK signaling antagonist 4).