Increased levels of serum immunoglobulin G1 (IgG1) in Pten+/– SHIP+/– (phosphatase with tensin homology/SH2-containing inositol phosphatase) mice. (a) Spontaneous increases in circulating serum IgG1 levels were detected in the sera of 8-week-old Pten+/– SHIP+/– mice, as compared to the other genotypes, and this pattern remained steady and elevated over time. (b) Serum levels of circulating immunoglobulin M (IgM) were not significantly increased over all genotypes at the 8-week point, but steadily increased, becoming significant at later time-points. (c) Levels of circulating immunoglobulin G2b (IgG2b) did not achieve statistical significance compared to all genotypes until the 24-week time-point. Values were representative of sera from at least nine animals per genotype, assessed in duplicate. Error bars represent the standard error of the mean (SEM) of the duplicate readings. *P < 0·05 compared with all genotypes.