The phrase "are indeed negative" is correct and usable in written English.
It can be used to emphasize that something is confirmed to be negative or unfavorable in a discussion or analysis.
Example: "The results of the experiment are indeed negative, indicating that the hypothesis was incorrect."
Alternatives: "are certainly negative" or "are clearly negative."
So is replicating negative results to check that they are, indeed, negative.
Normally miRNAs act as negative gene regulators and all of the miRNA-target links identified in this study are indeed negative.
Using this approach, we found that when spermatogonia present in one section express Smc6, the same cells in a neighboring section are indeed negative for LIN28.
Later in the day, there were indeed negative news items about his opponents, and Weinstein stopped by Nestor's desk to be sure that she'd seen them.
Immunoblotting analysis (Fig. 1D) confirmed that these cells with the pol λ −/− and pol λ −/−/pol β−/− double knockout genotypes were, indeed, negative for pol λ expression (lanes 2 and 4, top panel), whereas the wild-type and pol β −/− cells were positive (lanes 1 and 3, top panel).
Table 5 shows that δΦ is indeed negative for the reassignment from Val to Leu.
Two of our seven patients developing lymphomas were indeed negative for anti-Ro and anti-La.
We found that the BECLIN 1-positive cancers associated with the patients deceased during the study were indeed negative for vacuolar LC3 staining and highly expressing BCL-2.
As the result of this test was indeed negative, we find the statistical evidence as convincing as it can be although the final proof, of course, can only be experimental.
It is also likely that the majority of the negative genes are indeed true negatives and therefore re-screening the entire set of negatives would be an inefficient approach.
Importantly, these cells also did not display any expression of the BamH1 Z fragment leftward reading frame 1 (BZLF1) protein upon cross-linking, verifying that these cells are indeed EBV negative and do not enter lytic EBV replication, which is initiated by BZLF1 (Fig. 1C).
