Fig. 2

SPHK1 and SGPL1 expression in cytotoxic drug resistant gastroesophageal cancer cell lines. a All drug resistant cell lines showed increased SPHK1 mRNA expression relative to parental wild type line, and 4 out of 6 also showed decreased SGPL1 mRNA. Data shown is mean (+/- SEM) from 3 independent replicates per cell line from three different passages using Affymetrix Exon 1.0ST microarrays and validated by qRT-PCR (see Additional file 1: Additional information 2 and 3). *** p < 0.01 ** p < 0.05 (Student’s t-test). b Inverse correlation between SPHK1 and SGPL1 mRNA levels (R = -0.740, p = 0.022). Data shown is mean for all drug resistant cell lines and parental wild type lines, 3 independent replicates per cell line from three different passages measured by qRT-PCR (see also Additional file 1: Additional information 5). c Hypothesis of increased SPHK1 and decreased SGPL1 leading to increased S1P in gastro-oeosphageal cancer, promoting cell survival and hence cytotoxic drug resistance