*We have less tissue than 0,5mg but 500 ul is a comfortable volume to work with since we have to homogenize the sample with a motorized rotor-stator homogenizer that needs a big volume to homogenize the whole sample. And, afterwards, we have to split the volume into RNA and Protein samples, so 500ul enables a 200 and 200ul separate homogenates (~100ul gets lost as foam) which is a correct volume.