Is regrouping allowed here (ANOVA)?

Dear community

We measured the relative area of a protein (area protein/area tissue) in different compartments ( of a tissue piece (see VEGFA_...jpg in attachment). The compartments are related: Normal (pink) is next to IM Normal (green), IM Normal is next to IM Tumor (yellow) and IM Tumor is next to Cn Tumor (red). We did this for 33 NoLi, 128 De, 27 Pu, 91 Re, 93 Mi.

Now we want to compare the relative area between the different compartments with one-way ANOVA and Tukey HSD. But we also like to regroup two compartments into one (IM Tumor and IM Normal into IM). Can I just rename the levels or do I need to do other calculation as well (e.g. average the measurements)?

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