Myth-busting about first mass-produced human cell line

In Steve Silberman's Book Review of The Immortal Life of Henrietta Lacks (Nature 463, 610; 2010), two myths about HeLa cells are perpetuated.

Your lead-in claims that the death of Henrietta Lacks “led to the first immortal cell line”, but that distinction belongs to the L929 cell line, which was derived from mouse connective tissue and described almost a decade earlier (W. Earle J. Natl Cancer Inst. 4, 165–212; 1943). As Silberman notes, Lacks's was the first mass-produced human cell line. And HeLa's alleged growth “with mythological intensity... doubling their numbers every twenty-four hours...”, quoted from the book itself, is no different from the doubling time of cultured normal human cells (L. H. and P. S. Moorhead Exp. Cell Res. 25, 585–621; 1961).

The numbers of HeLa cells produced during the first few years of the line's existence in vitro were unremarkable because of the explant technique used at the time. Production of large numbers became possible several years later, with the introduction of the monolayer culture technique that is still in common use.