This bone has many positive osteoblasts that are clearly laying down bone ( partially-calcified thus able to sectioned without prior  decalcification)

Endochondral ossification. Interestingly, what seem to me to be hypertrophic chondrocytes, are positive for SP7.

Unless the nuclear positivity is non-specific, it seems that Schwann cell nuclei also express SOX4. Literature states that SOX4 is involved in the modulation of myelination: perhaps also in maintenance of myelin sheaths?

Positive oligodebdrocytes?

Also, there is a moderate Purkinje cell nuclear positivity.

Region of CA 3 hippocampus/fornix/lateral ventricle shown. Oligodendrocytes of the fornix appear to be mostly positive ( or are they all positive? Thus the blue nuclei will be fibrous astrocytes and mivroglia).

An identical pattern of positivity is seen in sections of human, rat, mouse and marmoset spleen.

A subpopulation of human stem cells have differentiated into SOX4 +ve cells .