Using tone rows is not the same as being twelve-tone or atonal, though. Obvious, but it needs to be pointed out. None of these late Shostakovich pieces are twelve tone or atonal.
Was just reading an analysis of the wonderful 12th quartet yesterday, coincidentally - the use of tone-rows here is very unusual, and it's not even really correct to call them rows (with the implication of a recurrent, rigid intervallic structure), as their interval structure is not consistent. It's really the momentary effect of chromatic saturation that Shostakovich is looking for with these brief 'rows', and he uses it as one extreme of a tonal continuum which encompasses the most euphonious tonality too. The opening 'row', for instance, finishes with a dominant-tonic into an entirely tonal D flat, and the only relevance it has to what follows immediately after is that the D flat major is inflected expressively by semitones which could be seen as hinting back to the 'row'.