Total RNA from cells were extracted using Trizol reagent (Life Technologies, Benicia, CA, USA). RT–PCR was performed using SuperScript One-Step RT–PCR Platinum Taq system (Life Technologies) with 50 ng RNA and one of the following primer pairs CK1/CK1R, CK2/CK2R, CK3/CK3R or CK1/CK3R (See Supplementary Information). RT–PCR products were separated on agarose gel, purified and re-amplified by PCR. PCR products were cleaned with ExoSAP-IT PCR product cleanup reagent (Affymetrix) and sequenced in both strains using BigDye Terminator 3.1 cycle sequencing kit (Life Technologies) as described (Ren et al, 2013 (link)). Quantitative RT–PCR (RT–qPCR) was performed using CK2/CK2R or CK-T/CK-R primer pairs (Supplementary Information). RT–qPCR was performed using Power SYBR Green reagents (Applied Biosystems, Foster City, CA, USA). Samples were assayed in triplicates as described (Schneeberger et al, 2014 (link)).