One study by Leyre (2012) reported an obvious excess of SK1 enzyme activity levels, compared with the other 2 studies [14]; the heterogeneity was so remarkable (P <0.00001, I2 = 96%) that it could not be altered by omitting any single study from the sensitivity analysis; therefore, we cannot draw a firm conclusion regarding a relationship between SK1 activity and cancer. The gene discussed is SPHK1; the disease is cancer.