1. The last sentence of the 3rd paragraph seems to be incomplete.
2. The authors state that: "Unfortunately none of the tested MYC antibodies revealed a specific staining pattern in the mouse testis (data not shown)." If this is true, can they explain which antibody they use in the IHC experiments (panels 1A,B,C,E,I) and how reliable the IHC results are?
3. The authors indicate in the results section that the absence of MYC from mouse germ cells "has never been corroborated at the protein level", but then perform RT-PCR to test its expression. A similar experiment (as described below) should be performed looking at MYC protein levels.
Methods to efficiently isolate mouse germ cells and to separate them from other cells are quite well established (e.g. PMIDs: 22144236, 19030797, 19685332, 10948556). A control western blot experiment to verify the IHC data is missing. The authors should separate germ cells from the other testicular cell types (or use an enrichment method) and compare MYC levels by western blot. Lysates from testicular cancer cells should also be included in the blot as an additional control. A internal reference protein (e.g. actin, tubulin, GAPDH) should be used for normalization of the samples, and CIP2A levels can also be used to correlate them to MYC expression.
The same point is true for 1F, G, H. The authors show mRNA levels, which confirms the findings in Ref.5, but do not test protein levels by western blot (as they claim in the results section).
4. The experiment in 1D is not qPCR (i.e. quantitative), but normal RT-PCR, and this should be corrected.