Question: Which actor in The 39 Steps also starred in the series The Strain?

<P0-S0> Rupert William Penry-Jones (born 22 September 1970) is an English actor, best known for his roles as Adam Carter in the BBC One spy drama series "Spooks", Clive Reader QC in the BBC One legal drama "Silk", policeman DI Joseph Chandler in the ITV murder mystery series "Whitechapel", and Mr. Quinlan in the FX horror series "The Strain". <SEP> <P1-S0> Doxorubicin (DXR) is a 14-hydroxylated version of daunorubicin, the immediate precursor of DXR in its biosynthetic pathway. <P1-S1>  Daunorubicin is more abundantly found as a natural product because it is produced by a number of different wild type strains of "streptomyces". <P1-S2>  In contrast, only one known non-wild type species, "streptomyces peucetius" subspecies "cesius" ATCC 27952, was initially found to be capable of producing the more widely used doxorubicin. <P1-S3>  This strain was created by Arcamone et al. in 1969 by mutating a strain producing daunorubicin, but not DXR, at least in detectable quantities. <P1-S4>  Subsequently, Hutchinson's group showed that under special environmental conditions, or by the introduction of genetic modifications, other strains of "streptomyces" can produce doxorubicin. <P1-S5>  His group has also cloned many of the genes required for DXR production, although not all of them have been fully characterized. <P1-S6>  In 1996, Strohl's group discovered, isolated and characterized dox A, the gene encoding the enzyme that converts daunorubicin into DXR. <P1-S7>  By 1999, they produced recombinant Dox A, a Cytochrome P450 oxidase, and found that it catalyzes multiple steps in DXR biosynthesis, including steps leading to daunorubicin. <P1-S8>  This was significant because it became clear that all daunorubicin producing strains have the necessary genes to produce DXR, the much more therapeutically important of the two. <P1-S9>  Hutchinson's group went on to develop methods to improve the yield of DXR, from the fermentation process used in its commercial production, not only by introducing Dox A encoding plasmids, but also by introducing mutations to deactivate enzymes that shunt DXR precursors to less useful products, for example baumycin-like glycosides. <P1-S10>  Some triple mutants, that also over-expressed Dox A, were able to double the yield of DXR. <P1-S11>  This is of more than academic interest because at that time DXR cost about $1.37 million per kg and current production in 1999 was 225 kg per annum. <P1-S12>  More efficient production techniques have brought the price down to $1.1 million per kg for the non-liposomal formulation. <P1-S13>  Although DXR can be produced semi-synthetically from daunorubicin, the process involves electrophilic bromination and multiple steps and the yield is poor. <P1-S14>  Since daunorubicin is produced by fermentation, it would be ideal if the bacteria could complete DXR synthesis more effectively. <SEP> <P2-S0> Stephen Critchlow is an English actor, notable for his work in the theatre and appearances on radio series such as "Truly, Madly, Bletchley", "The Way We Live Right Now" and "Spats", along with radio episodes of "Torchwood" ("Lost Souls") and "Doctor Who" ("The Nowhere Place"). <P2-S1>  He has also appeared in "" as Kenneth Horne and is currently appearing in the West End version of "The 39 Steps". <SEP> <P3-S0>  It was written by Lizzie Mickery, directed by James Hawes, and filmed on location in Scotland, starring Rupert Penry-Jones, Lydia Leonard, David Haig, Eddie Marsan, and Patrick Malahide. <P3-S1> The 39 Steps is a 2008 British television adventure thriller feature-length adaptation of the John Buchan novel "The Thirty-Nine Steps" produced by the BBC. <P3-S2>  Following three screen versions of the novel and the 1952 and 1977 television adaptations of "The Three Hostages", Penry-Jones became the sixth actor to portray Hannay on screen. <P3-S3>  This adaptation is set on the eve of the First World War and sees mining engineer Richard Hannay caught up in an espionage conspiracy following the death of a British spy in his flat.