Table 1.

Effect sizes with standard errors for the influence of oxygen condition on the expression levels of EGFR, HER2, HER3, and HER4 in all HNSCC cell lines. The effect size is only reported if there was a significant difference in overton and ΔMFI of HER receptors between normoxia and hypoxia (P‐value ‘effect oxygen’). The effect size represents the difference in mean overton and ΔMFI between normoxia and hypoxia. Positive and negative effect sizes, respectively, indicate an increase and decrease under hypoxia compared to normoxia. The P‐value shows the significance, testing the null hypothesis that the effect size equals zero. P‐values ≤ ≤0.05 are indicated in bold. /, effect size was not shown in case there was no significant effect of oxygen condition on the outcome

	% Positive cells (overton)			Expression level (ΔMFI)
	P‐value effect oxygen	Effect size (%)	P‐value effect size	P‐value effect oxygen	Effect size (ΔMFI)	P‐value effect size
EGFR	0.006	5.95 ± 2.03	0.003	< 0.001	463.35 ± 64.65	< 0.001
HER2	0.065	/	/	< 0.001	483.62 ± 80.93	< 0.001
HER3	< 0.001	−12.95 ± 1.95	< 0.001	0.425	/	/
HER4	0.377	/	/	0.300	/	/