Call:
glm(formula = Expression ~ genotype + prep.no + sex, family = poisson(link = "log"),
data = ERAPdata)

Deviance Residuals:
 Min        1Q    Median        3Q       Max
-24.9946   -5.8912   -0.3892    4.6403   25.2830

Coefficients:
             Estimate Std. Error  z value Pr(>|z|)
(Intercept)  8.081717   0.004232 1909.463  < 2e-16 ***
genotype1   -0.025497   0.003396   -7.507 6.05e-14 ***
genotype2   -0.091365   0.007384  -12.374  < 2e-16 ***
prep.no2    -0.006075   0.005313   -1.143 0.252864
prep.no3     0.001074   0.005412    0.198 0.842676
prep.no4    -0.007511   0.005791   -1.297 0.194621
prep.no5    -0.006958   0.005539   -1.256 0.209031
prep.no6     0.023217   0.005812    3.994 6.49e-05 ***
prep.no7     0.026062   0.007411    3.517 0.000437 ***
sex1         0.015740   0.003433    4.584 4.56e-06 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

(Dispersion parameter for poisson family taken to be 1)

    Null deviance: 9662.4  on 131  degrees of freedom
Residual deviance: 9384.5  on 122  degrees of freedom
AIC: 10711

Number of Fisher Scoring iterations: 4